Observatorio ARVAL

Astronomy for South Florida

Fair Weather Astronomy
Calendar of Astronomical Events
Solar Activity
Links
Recent Astronomical Events
Notes (A glossary of important terms for the sky observer)

Meteorology for South Florida and the Caribbean (Separate Page)
Near-Earth Objects (NEOs) (Separate Page)




Fair Weather Astronomy:


Current Lunar Phase:
Current Lunar Phase


  (Date and Time in Florida)


Simulated Lunar Phase at the current time
by the US Naval Observatory
[North up, West to the right]
[Click to enlarge]



Weather Images from NOAA Satellite Services Division:
GOES East Satellite Imagery: (updated every 30 min.)
Southeast US: Visible - Infrared Channel 4 - Rainbow - Water Vapor [Resolution 3 Km, 24° to 33° N, 94° to 76° W]

Weather Image Loops from NOAA Satellite Services Division:   [Adobe Flash]
Southeast US: Visible - Infrared Channel 4 - Rainbow - Water Vapor [Resolution 3 Km, 24° to 33° N, 94° to 76° W]


Images from NOAA Satellite Services Division: (updated every 30 min.)
GOES-East Miami, FL WFO Imagery: Visible - Infrared Channel 4 - Rainbow [Resolution 1 Km, 24° to 28° N, 84° to 78° W]

Image Loops from NOAA Satellite Services Division:   [Adobe Flash]
GOES-East Miami, FL WFO Imagery: Visible - Infrared Channel 4 - Rainbow [Resolution 1 Km, 24° to 28° N, 84° to 78° W]

[The most detailed GOES East information on South Florida]


National Weather Service (NWS) - Southern Region Headquarters (7 days):
Key Biscayne (25.69° N, 80.17° W)
Cutler (25.63° N, 80.3° W)
Florida City, Everglades National Park entrance (25.44° N, 80.48° W)

NWS Southern Florida - Hourly Graphical Weather Forecasts (3 days):
Key Biscayne (25.69° N, 80.17° W)
Cutler (25.61° N, 80.33° W)
18 Miles W of Florida City, near Pa-hay-okee Overlook (25.47° N, 80.81° W)


Weather Underground:

Click for Key Biscayne, Florida Forecast   Click for Key Biscayne, Florida Forecast

Click for Kendall, Florida Forecast   Click for Kendall, Florida Forecast

Weather Underground Full Screen Weather (Active Tropical Storm Advisories, Radar and Satellite Imagery)


Clear Sky Charts for Canada, USA and parts of Mexico - by Attilla Danko:

Bill Sadowski Park Clear Sky Chart: (Palmetto Bay, 25° 36.52' N, 80° 19.09' W)

Bill Sadowski Park Clear Sky Chart




Southern Cross Astronomical Society (SCAS) - Saturday Nite Live:

Weather permitting, meet the friendly Southern Cross Astros, 8 to 10 PM every Saturday evening all year at the popular outdoor SCAS Observatory in Miami-Dade's Bill Sadowski Park & Nature Center, SW 176th St. / SW 79th Ave., 1/2 mile west of Old Cutler Road in Palmetto Bay (W 80° 19.2', N 25° 36.5'). Free viewing.

Under the darkest skies nearest to downtown, you might see a satellite, a sudden brilliant meteor or the International Space Station in addition to the seasonal planets, the magical Moon and dazzling constellations. Enjoy the beauty overhead in SCAS state-of-the-art hi-tech equipment, including the largest telescope in Miami-Dade County for public use.

Check the weather before you leave home as June through October is thunderstorm season in Florida!
Bring your family, friends, house guests, snacks, lawn chairs and bug cream (chemical aerosals remove the coating on the expensive telescope mirrors and lenses).
Director Barb Yager advises you to wear jeans, sport shoes, and bring a long-sleeved top to our educational evening under the stars....  It's the best deal in town!
Bring your telescope!  If you need help, our SCAS techs will come to your rescue.


NO LIGHTS, litter, alcohol or pets allowed in the Nature Preserve. Please turn off car lights when entering the park.
The SCAS telescope deck is accessible to the disabled with convenient parking.

Groups of 20+, please make your reservations on the SCAS Hotline at 305-661-1375 so we know you are coming.

The Southern Cross Astronomical Society Bulletin Board (SCASmail) will post notices about upcoming public events and reports on those events.

Check the SCAS Stargazer in Sunday's Miami Herald Tropical Life - Section M, our community service for more than 23 years.

See the Interactive Sky Chart for Miami, Florida (Sky & Telescope),
Sky and Satellites for Cutler, Florida (Heavens-Above),
Sky and Satellites for Key Biscayne, Florida (Heavens-Above),
Satellite Flybys for Palmetto Bay, Florida (SpaceweatherPhone.com),
Satellite Flybys for Key Biscayne, Florida (SpaceweatherPhone.com).

See josebellas.com (José Bellas, SCAS)

Vea El blog de astroheredero (Carlos Heredero, SCAS)


To see the dates of the Lunar Phases for this month (or any other):
   U.S. Naval Observatory - Phases of the Moon
   U.S. Naval Observatory - Sunrise/Sunset/Twilight and Moonrise/Moonset/Phase for One Day
   U.S. Naval Observatory - Sunrise/Sunset/Twilight and Moonrise/Moonset for One Year
   Moon Phase Calculator (Universe Online, McDonald Observatory, University of Texas)
   Lunar Data for Cutler, Florida (Heavens-Above)

Lunar Phases repeat every 29.53 days; the Synodic Period of the Moon, called a "Lunation".
   The Moon orbits the Earth at an average distance of 384,401 Km.

The Moon moves against the firmament some 13° to the East every day.
   Thus it rises and sets, in average, some 53 minutes later every day.

It is possible to observe the sky without moonlight during the first part of the night,
   from the day of the Last Quarter, when the Moon rises at midnight, to the day of the New Moon,
   when it sets at sunset.

It is possible to observe the sky without moonlight during the last part of the night,
   from the day of the New Moon, when it rises at dawn, to the day of the First Quarter,
   when the Moon sets at midnight.

Eastern Standard Time in the U.S.A. = Universal Time Coordinated (UTC) - 5 hours
   (- 4 hours during Daylight Saving Time)
   A service of the National Institute of Standards and Technology (NIST)


Please help stopping light pollution!   See the Luminic Map of Florida.




For excellent video tutorials on Cosmology, Astronomy and more, see Khan Academy - Cosmology and Astronomy




Calendar of Astronomical Events:


Venus was at Superior Conjunction on March 28 '13.
It was too close to the Sun to be observed. Later it will be possible to observe after sunset, above the Western horizon, higher every day.
[Next on October 25 '14]


Mars was at Solar Conjunction on April 17 '13.
It was too close to the Sun to be observed. Later it was possible to observe before sunrise, very low above the Eastern horizon, higher every day.
[Next on June 14 '15]


The Earth's Aphelium, that marks its maximum distance to the Sun, was on July 5 '13.
[Next on July 4 '14].
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.


Neptune was at Opposition on August 26 '13.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset above the Eastern horizon, higher every day.
[Next on August 29 '14]


The Autumn Equinox, that marks the beginning of Autumn in the Northern hemisphere,
and the beginning of Fall in the Southern hemisphere, was on September 22 '13, at 20:44 UT (16:44 EDT).
The Sun will have a Southern Declination until the Winter Equinox [on March 20 '14]. Day and night were of the same length.
[Next on September 23 '14, at 02:29 UT (22:29 EDT)]
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.
See Equinoxes at the U.S. Naval Observatory.
See Equal day and night - but not quite (timeanddate.com).


Uranus was at Opposition on October 3 '13.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset above the Eaestern horizon, lower every day.
[Next on October 7 '14]


Venus was at Maximum Eastern Elongation on November 1 '13.
It was possible to observe after sunset above the western horizon, lower every day.
[Next on June 6 '15]


Saturn was at Solar Conjunction on November 6 '13.
It was too close to the Sun to be observed. Later it was possible to observe after sunset above the Western horizon, higher every day.
[Next on November 18 '14]


The Winter Solstice, that marks the beginning of Winter in the Northern hemisphere,
and the beginning of Summer in the Southern hemisphere, was on December 21 '13, at 17:11 UT (12:11 EST).
The Sun reached its maximum Southern Declination (near 23.5° S). It will be the shortest day and longest night for the year in the Northern hemisphere, the longest day and shortest night for the year in the Southern hemisphere.
[Next on December 21 '14, 23:03 UT (18:03 EST)]
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.
See The December Solstice (timeanddate.com).
See Winter Solstice (Starman by Jay Ryan) (in ARVAL).


The Earth's Perihelium, that marks its closest distance to the Sun, was on January 4 '14, 12 UT (07 EST).
[Next on January 4 '15, 07 UT (02 EST)]
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.


Jupiter was at Opposition on January 5 '14.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset above the Eastern horizon, higher every day.
[Next on February 6 '15]


Venus; was at Inferior Conjunction on January 11 '14.
It was too close to the Sun to be observed. Later it was possible to observe before sunrise, low in the Eastern horizon, higher each day.
[Next on August 15 '15]


On February 15 '14 it was 450 years from the birth in Pisa, Italia, of Galileo Galilei (1564-1642); The first scientist.
See The Galileo Project (Rice University), and Dialogue Concerning the Two Chief World Systems.


Neptune was at Solar Conjunction on February 23 '14.
It was too close to the Sun to be observed. Later it will be possible to observe before sunrise, very low above the Eastern horizon, higher every day.
[Next on February 25 '15]


Eastern Standard Time (EST = UT-5) ended and Eastern Daylight Saving Time (EDT = UT-4) started on March 9 '14 at 02:00. Clocks turned forward 1 hour at this time.
See When do we change our clocks? (Daylight Saving Time - History, rationale, laws & dates).
[Standard Time will again start on November 2 '14]


The Winter Equinox, that marks the beginning of Spring in the Northern hemisphere,
and the beginning of Autumn in the Southern hemisphere, was on March 20 '14, at 16:57 UT (12:57 EDT).
The Sun crossed to the North of the Celestial Equator.
The Sun will have a Northern Declination until the Autumn Equinox [on September 23 '14]. Day and night were of the same length.
[Next on March 20 '15, at 22:45 UT (18:45 EDT)]
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.
See Equinoxes at the U.S. Naval Observatory.
See Equal day and night - but not quite (timeanddate.com).


Venus was at Maximum Western Elongation on March 22 '14.
It will be possible to observe before sunrise above the eastern horizon, lower every day.
[Next on October 26 '15]


Uranus; was at Solar Conjunction on April 2 '14.
Later it will be possible to observe before sunrise above the eastern horizon, higher every day.
[Next on April 6 '15]


Mars was at Opposition on April 8 '14, 20:57 UT (16:57 EDT); With an equatorial diameter of ~15", and a Magnitude of -1.5 in the Virgo constellation.
Mars rises at 19:33, transits at 01:30 and sets at 07:15 on April 9 '14.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset, above the Eastern horizon, higher every day.
On April 14 '14 Mars was 0.6176 AU away (92.39 million Kilometers), 15.16" in diameter.
The closest Opposition in historical times was on August 27 2003, the next closer will be in August 15 2050 (diameter ~25"). See Close Encounter with Mars (Science@NASA, Jan 26 '10).
See Primer on Mars Oppositions (IMCCE), and Mars Oppositions (SEDS).
See also The Opposition of Mars (Science@NASA, March 28 '14)
[Next on May 22 '16]


Minor Planet 1 Ceres was at Opposition on April 15 '14.
Its magnitude was 7, it was at R.A. 13h 57m, Dec. 2° 57' N, in the constellation Virgo, halfway between the stars Spica (Alpha Virginis) and Arcturus (Alpha Bootis). It transited at 01:45.
1 Ceres has an orbital period of 4.60 years and a diameter of 952.4 Km.
See 1 Ceres (Wikipedia), JPL Small-Body Database Browser - 1 Ceres, and Ceres: The Dwarf Planet,
See Dawn Mission (Ion Propulsion, Asteroids Ceres and Vesta, from September 2007 to July 2015),
Asteroids & Comets Amateur Observer's Calendar.
[Next on July 25 '15]


Mercury was at Superior Conjunction on April 25 '14.
It was too close to the Sun to be observed. Later it will be posible to observe after sunset, low in the Western horizon, higher each day.
[Next on August 8 '14]


First Quarter Moon; May 7 '14 at 03:15 UT (23:15 EDT on May 8 '14).


Saturn was at Opposition on May 10 '14.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset rising above the Eastern horizon, higher every day.
[Next on May 23 '15]


Full Moon; May 14 '14 at 19:16 UT (15:16 EDT).


Last Quarter Moon; May 21 '14 at 12:59 UT (08:59 EDT).


Mercury was at Maximum in Eastern Elongation on May 25 '14.
It was possible to observe after sunset above the Western horizon, lower every day.
[Next on September 21 '14]


New Moon; May 28 '14 at 18:40 UT (14:40 EDT).


First Quarter Moon; June 5 '14 at 20:39 UT (16:39 EDT).


Full Moon; June 13 '14 at 04:11 UT (00:11 EDT).


Last Quarter Moon; June 19 '14 at 18:39 UT (14:39 EDT).


Mercury was at Inferior Conjunction on June 19 '14.
It was too close to the Sun to be observed. Later it will be possible to observe before sunrise, low above the Eastern horizon, higher every day.
[Next on October 16 '14]


The Summer Solstice, that marks the beginning of Summer in the Northern hemisphere,
and the beginning of Winter in the Southern hemisphere, was on June 21 '14, at 10:51 UT (06:51 EDT).
The Sun reached its maximum Northern Declination (near 23.5° N). It is the longest day and shortest night for the year in the Northern hemisphere, the shortest day and longest night for the year in the Southern hemisphere.
[Next on June 21 '15, 16:38 UT (12:38 EDT)]
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.
See The June Solstice (timeanddate.com).
See Summer Solstice (Starman by Jay Ryan) (in ARVAL).


New Moon; June 27 '14 at 08:08 UT (04:08 EDT).


The Earth's Aphelium, that marks its maximum distance to the Sun, was on July 4 '14.
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.


Pluto was at Opposition on July 4 '14.
It was opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It was possible to observe after sunset rising above the Eastern horizon, higher every day.
[Next on July 6 '15]


First Quarter Moon; July 5 '14 at 11:59 UT (07:59 EDT).


Full Moon; July 12 '14 at 11:25 UT (07:25 EDT).


Mercury was at Maximum in Western Elongation on July 12 '14.
It was possible to observe before sunrise above the eastern horizon, lower every day.
[Next on November 1 '14]


Last Quarter Moon; July 19 '14 at 02:08 UT (July 18 '14 at 22:08 EDT).


Jupiter was at Solar Conjunction on July 24 '14.
It was too close to the Sun to be observed. Later it will be possible to observe before sunrise, very low above the Eastern horizon, higher every day.
[Next on August 26 '15]


New Moon; July 26 '14 at 22:14 UT (18:14 EDT).


First Quarter Moon; August 4 '14 at 00:50 UT (Agust 3 '14 20:50 EDT).


Mercury will be at Superior Conjunction on August 8 '14.
It will be too close to the Sun to be observed. Later it will be posible to observe after sunset, low in the Western horizon, higher each day.


Full Moon; August 10 '14 at 18:09 UT (14:09 EDT).


Last Quarter Moon; August 17 '14 at 12:26 UT (08:26 EDT).


New Moon; August 25 '14 at 14:13 UT (10:13 EDT).


Neptune will be at Opposition on August 29 '14.
It will be opposite to the Sun in the sky, raising at sunset and setting at dawn; in a straight line with the Sun and the Earth. It will be possible to observe after sunset above the Eastern horizon, higher every day.




Safe Solar Viewing:

SCAS ex-President Lester Shalloway M.D. & staff, arrange safe, professional solar equipment (telescope & video) at the Miami MetroZoo, Saturdays 10 AM to Noon, near the waterfall in front of the ticket entrance at 12400 SW 152nd St. Free viewing.

You may see the powerful, nuclear explosions - Sun spots and prominences - erupting in slow motion before your eyes, safely....  93 million miles away!

Check the SCAS Hotline at 305-661-1375 for the latest update at 9:30 AM Saturdays.




Solar Activity:

There is a cycle of activity of the Sun itself, of some 11 years, but not very constant in length or intensity. Some of the effects of the Solar activity on the Earth's atmosphere are now just beginning to be studied. The reconstructions of ancient climates reveal a close correlation between Solar activity and temperatures on Earth.

ISES - Solar Cycle Sunspot Number Progression
International Space Environment Service (ISES), Solar Cycle Sunspot Number Progression

ISES - Solar Cycle Ap Progression
International Space Environment Service (ISES), Solar Cycle Planetary Index, Ap Progression
[The Ap geomagnetic index is an indirect measure of the Solar magnetic field]

May 8, 2009 -- At the beginning of 2011, we were near a minimum of the Solar Cycle 23 (in December 2008) that was "late to arrive", the next Solar maximum was then expected to occur in May 2013.
[A second peak in sunspot number occurred in December 2013]
See Solar Cycle Progression and Prediction Center (NOAA / NWS Space Weather Prediction Center)


Yearly averaged sunspot number (1610-2013)
The yearly averaged sunspot number for a period of 400 years (1610-2013)
The Maunder Minimum is shown during the second half of the 17th century
Solar Physics Group, NASA Marshall Space Flight Center [November 1, 2013]


Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades - a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.
The last solar minimum should have ended in 2010, but something peculiar has been happening. Although solar minimums normally last about 16 months, Solar Cycle 23 stretched over 26 months - the longest in a century. One reason, according to a paper submitted to the International Astronomical Union Symposium No. 273, an online colloquium, Long-term Evolution of Sunspot Magnetic Fields (Matthew Penn, William Livingston, 3 Sep. 2010), is that the magnetic field strength of sunspots appears to be waning.
The phenomenon has happened before. Sunspots disappeared almost entirely between 1645 and 1715 during a period called the Maunder Minimum, which coincided with decades of lower-than-normal temperatures in Europe nicknamed the Little Ice Age. But Livingston cautions that the zero-sunspot prediction could be premature. "It may not happen," he says. "Only the passage of time will tell whether the solar cycle will pick up."
See Say Goodbye to Sunspots? (Phil Berardelli, ScienceNOW, 14 September 2010).
For a discussion, see The sun is still in a slump - still not conforming to NOAA "consensus" forecasts (Anthony Watts, Watts Up With That?, January 5, 2011).

In the Sun, a missing jet stream, fading spots, and slower activity near the poles say that our Sun is heading for a rest period even as it is acting up for the first time in years, according to scientists at the National Solar Observatory (NSO) and the Air Force Research Laboratory (AFRL).
As the current sunspot cycle, Cycle 24, begins to ramp up toward maximum, independent studies of the solar interior, visible surface, and the corona indicate that the next 11-year solar sunspot cycle, Cycle 25, will be greatly reduced or may not happen at all.
See What's Down With The Sun? - Major Drop In Solar Activity Predicted (NSO Press Release, June 14, 2011).
For a discussion, see "All three of these lines of research to point to the familiar sunspot cycle shutting down for a while." (Anthony Watts, Watts Up With That?, June 15, 2011).

"The Maunder Minimum: Early records of sunspots indicate that the Sun went through a period of inactivity in the late 17th century. Very few sunspots were seen on the Sun from about 1645 to 1715 (JPEG image, 38 Kb). Although the observations were not as extensive as in later years, the Sun was in fact well observed during this time and this lack of sunspots is well documented. This period of solar inactivity also corresponds to a climatic period called the "Little Ice Age" when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes. There is evidence that the Sun has had similar periods of inactivity in the more distant past. The connection between solar activity and terrestrial climate is an area of on-going research."
See The Sunspot Cycle and Solar Cycle Prediction (NASA Solar Physics, Marshall Space Flight Center).


[SOHO - Visible Light]   [SOHO - Hydrogen-Alpha]   [SOHO - Magnetic Fields]

Click on an image above for the latest close up view of the Sun
(Visible Light, Hydrogen-Alpha and Magnetic Fields. Solar and Heliospheric Observatory - SOHO Satellite).
See Solar and Heliospheric Observatory - SOHO site (ESA and NASA) for more information.
See SpaceWeather.com (NASA) for more information.
See Solar Terrestrial Activity Report (Jan Alvestad) for more information.




See Observatorio ARVAL: Solar System Data

See eSky Planet Wheel (The Electronic Sky guide to the visibility of the planets in the sky)

See Hubblesite - Tonight's Sky (Monthly stargazing guide to constellations, planets, cosmic events and more)

See Science@NASA (Science Headline News)

See StarDate Online - Sky Almanac (Your Guide to the Universe. McDonald Observatory, University of Texas)

See CalSKY - The Calculated Sky (On-line Configurable Astronomical and Space Calendar)

See The Sky of Cutler, Florida (Sky and Telescope, SkyTonight - Interactive Sky Chart, Java applet)

See Almanac v3.0 - Cutler, Florida (Sky and Telescope, Interactive Observing Tools, Java applet)

See Heavens-Above: Planets Summary for Cutler, Florida
See Heavens-Above: Planets Summary for Key Biscayne, Florida
See Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2020 at the US Naval Observatory.




Recent Astronomical Events:


Total Lunar Eclipse; April 15 '14.
A somewhat deep Total Lunar Eclipse, with a magnitude of 1.2907.
Was easily visible to the naked eye as a reddish shadow, deeper towards the north of the Moon.

Start of entrance to the Umbra: 05:58:19 UT (01:58:19 EDT)
Start of the Total Eclipse: 07:06:47 UT (03:06:47 EDT)
Maximum Eclipse: 07:45:40 UT (03:45:40 EDT)
End of the Total Eclipse: 08:24:35 UT (04:24:35 EDT)
End of exit from the Umbra: 09:33:04 UT (05:33:04 EDT)
The Moon set at 07:03 EDT

See Total Lunar Eclipse of Apr. 15, 2014 (NASA Eclipse Web Site, Fred Espenak)

Total Lunar Eclipse - Miami, April 15 '14 03:54 UT
Total Lunar Eclipse - Miami, April 15 '14 07:54 UT (03:54 EDT)
[The star northeast of the Moon is SAO 139401 (76 Virginis), Mag. 5.2]
[Canon EOS Rebel T1i, 250mm f5.6, ISO 1600, 1 sec.]


So begins a lunar eclipse tetrad - a series of 4 consecutive total eclipses occurring at approximately six month intervals. The total eclipse of April 15, 2014, will be followed by another on Oct. 8, 2014, and another on April 4, 2015, and another on Sept. 28 2015.

See A Tetrad of Lunar Eclipses (NASA Science, March 27, 2014)


Partial Solar Eclipse at sunrise on November 3 '13.
Visible from the East coast of the USA and the Caribbean to the East of Africa at sunset.

For Miami, FL:
Sunrise: 06:30 EST, Azimut: 107°
Max. Eclipse: 11:32 UT (06:32 EST)
Eclipse Ends: 12:02 UT (07:02 EST)
Eclipse Magnitude: 0.476 (fraction of the Sun's diameter occulted by the Moon)
Eclipse Obscuration: 0.365 (fraction of the Sun's area occulted by the Moon)

Partial Solar Eclipse - Miami, November 3 '13 11:30 UT
Partial Solar Eclipse - Miami, November 3 '13 11:30 UT (06:30 EST)

Warning:
Never observe the Sun directly, or with optical instruments, without using the essential special filters, because it would result in permanent damage to your sight.
Do not use a solar filter mounted in the eyepiece of a telescope; This type of filter is dangerous!   (it might break with the heat of the Sun)
Use only the solar filters of a larger diameter, to mount in the objective.

"The final event of 2013 is the most interesting eclipse of the year. It is one of the rare hybrid or annular/total eclipses in which some sections of the path are annular while other parts are total."

See Hybrid Solar Eclipse of 2013 Nov 03 (NASA - Eclipses During 2013)
and Partial Solar Eclipse Sunday Morning, Nov. 3rd (Alan MacRobert. October 24, 2013. Sky & Telescope)


Comet 2012 S1 (ISON) was at Perihelion on November 28 '13 at 18:35 UT (13:35 EST).
It could have reached naked-eye visibility from around the 10th of November until disappearing in the morning twilight around November 21 '13. Between December 10th and 14th the comet would be best seen just before dawn after the Moon sets.
See C/2012 S1 (ISON) (IAU Minor Planet Center),
Comet 2012 S1 was discovered in September of 2012 by Vitali Nevski of Belarus and Artyom Novichonok of Russia using a telescope which is part of the International Scientific Optical Network (ISON), its official designation was C/2012 S1.
Comet C/2012 S1 ISON (Heavens-Above),
Comet ISON is Coming (Michael S. Kelley, January 31, 2013),
Comet ISON, March 2013 Update (Michael S. Kelley, March 29, 2013),
June 2013 Assessment of Comet ISON (Observing Blog - Sky & Telescope, June 13, 2013),
Comet ISON emerges from sun's glare not as bright as hoped (EarthSky, Deborah Byrd, September 17, 2013),
Comet ISON: A Viewing Guide from Now to Perihelion (Universe Today, David Dickinson, September 23, 2013)
Comet ISON Appears Intact (HubbleSite - NewsCenter, October 17, 2013))
Updates on Comet ISON (Alan MacRobert, Observing - Comets - Sky & Telescope, November 2013)
Comet ISON Comes to Life! (Tony Flanders, Observing - Comets - Sky & Telescope, November 14th 2013)
Comet ISON: What's Next? (NASA Science, Updated on Nov. 16, 2013)
NASA Comet ISON Observing Campaign (CIOC)
Distance & Speed - LIVE Information (Comet ISON 2013, NASA's Jet Propulsion Laboratory)

Apparently, Comet 2012 S1 (ISON) broke up at 17:36 UT, Nov. 28 '13 (SOHO), just before perihelion.
See SOHO coronagraph movie (November 28 '13, 11:36 UT to 20:36 UT) (NASA - SpaceWeather.com).
Compare the images at 17:24 UT, 17:36 UT, 17:48 UT (SOHO).
However, a fraction of the comet survived for some hours.
See 00:02 UT, Nov. 29 '13 (Solar and Heliospheric Observatory - SOHO).
See SOHO coronagraph movie (Nov. 27 '13, 01:41 UT to Nov. 29 '13, 18:18 UT) (NASA Science, Nov. 29 '13).
See What Happened to Comet ISON? (NASA Science, Dec. 4, 2013)


Jupiter and Venus were in conjunction (some 1° apart) on May 28 '13.
They could be observed with binoculars or a small telescope, before sunset, above the western horizon, in Taurus. Jupiter (diameter 32") was at Mag. -1.9, Venus (diameter 10"), much brighter, was at Mag. -3.9 and 1° to the South of Jupiter. Venus set at 21:19 and Jupiter at 21:15. The Sun set to the West at 20:06.
Calculations with TheSky from Software Bisque, version 6.


Transit of Venus:
On June 5 '12, from Miami we were able (but for the clouds) to observe the beginning of the event that started with
the First Contact at 18:04:37 EDT (22:04:37 UT) (Alt. 26°).
The Second Contact at 18:22:26 EDT (22:22:26 UT) (Alt. 22°).
Sunset was at 20:10 EDT in Miami.
The Greatest Transit was at 21:29:36 EDT (01:29:36 UT on June 6) (Geocentric).
The Third Contact was at 00:31:39 EDT on June 6 (04:31:39 UT on June 6) (Geocentric).
The Fourth Contact was at 00:49:35 EDT on June 6 (04:49:35 UT on June 6) (Geocentric).
Mercury passed some 9' North of the Sun's disk center.
Mercury had a diameter of some 58" and the Sun of some 31.5'.
At the moment of the First Contact the Sun was some 26° above the Western horizon (Az. 282°).
At the moment of the Second Contact the Sun was some 22° above the Western horizon (Az. 281°).

The Southern Cross Astronomical Society (SCAS) offered public viewing for the transit at 6-8 p.m. at:
The western parking lot of the Miami Metro Zoo, 12400 SW 152 St.
The rooftop of the FIU main campus garage -- free parking -- west side of SW 109 Ave./SW 8 St.

See The 2012 Transit of Venus NASA Eclipse Website, Goddard Space Flight Center, Fred Espenak.
See 2004 and 2012 Transits of Venus NASA Eclipse Website, Goddard Space Flight Center, Fred Espenak.
See 2012 Transit of Venus - Table 2b NASA Eclipse Website, Goddard Space Flight Center, Fred Espenak.
See The 2012 Transit of Venus Science@NASA, May 18, 2012.
See Transit of Venus: June 5-6, 2012 Sky & Telescope, March 4, 2012.
See Transit of Venus, Sun-Earth Day 2012 Webcasts, NASA Goddard Space Flight Center.
See ISS Transit of Venus NASA Science, May 31, 2012.
See Venus Transit Live W.M. Keck Observatory.

See Time lapse video of Venus transit seen from SDO YouTube, NASA Solar Dynamics Observatory.

See Transit of Venus in ARVAL, Astrophotography with the Meade LPI Digital Camera, June 8, 2004.

Warning:
Never observe the Sun directly, or with optical instruments, without using the essential special filters, because it would result in permanent damage to your sight.
Do not use a solar filter mounted in the eyepiece of a telescope; This type of filter is dangerous!   (it might break with the heat of the Sun)
Use only the solar filters of a larger diameter, to mount in the objective.


Partial Lunar Eclipse; June 4 '12.
Penumbral Eclipse Begins: 04:48:09 EDT
Partial Eclipse Begins: 05:59:53 EDT
Sunrise: 06:28 EDT
Moon Sets: 06:33 EDT
Greatest Eclipse: 07:03:13 EDT
Partial Eclipse Ends: 08:06:30 EDT
Penumbral Eclipse Ends: 09:18:17 EDT

See Partial Lunar Eclipse of June 4 '12 (NASA Eclipse Web Site, Fred Espenak)


On Friday, January 28 '11, 5 to 9 PM, SCAS hosted our Tropical Star Party at Bill Baggs State Park, near the Key Biscayne Lighthouse. Visitors observed Jupiter, Uranus, the Andromeda Galaxy and various star clusters through our telescopes. Jupiter set at 21:56, Uranus at 21:42. Sunset was at 6:01 PM.
See Southern Cross Astronomical Society


Total Eclipse of the Moon, December 21 '10: (in Taurus)

                      Miami, Florida
                     W 80° 11', N 25° 46'

                       Eastern Standard Time      Moon's
                                     h  m    Azimuth°  Altitude°
Moonrise               2010 Dec 20  17:06       63.1   ----
Moon enters penumbra   2010 Dec 21  00:29      244.1   85.7
Moon enters umbra      2010 Dec 21  01:33      266.8   71.9  <-- Visible eclipse starts
Moon enters totality   2010 Dec 21  02:41      274.3   56.9
Middle of eclipse      2010 Dec 21  03:17      276.6   49.0  <-- Darkest eclipse
Moon leaves totality   2010 Dec 21  03:53      279.6   41.0
Moon leaves umbra      2010 Dec 21  05:01      284.6   25.7  <-- Visible eclipse ends
Moon leaves penumbra   2010 Dec 21  06:04      289.5   13.6
Moonset                2010 Dec 21  07:16      296.2   ----
Eclipse Predictions from NASA GSFC Eclipse Web Site

This eclipse was visible in the Central Pacific Ocean and America. The eclipse was darker to the South of the Moon because it passed North of the center of the umbra projected by the Earth.
Betelgeuse (Alpha Orionis) was some 16° South of the Moon.

For the exact times at your locality, you can use the NASA Eclipse Web Site.
For more information and graphics, see NASA - Total Lunar Eclipse December 21, 2010, NASA/GSFC,
and Solstice Lunar Eclipse, Science@NASA, December 17, 2010.


Periodic Comet 103P/Hartley 2:
It is a periodic comet with an elliptical orbit (visiting the Sun every 6.46 years), it will be high in the evening sky when at its best throughout October 2010, glowing at perhaps 6th or 5th magnitude.
It should be dimly visible to the unaided eye from very dark locations, and visible in binoculars and telescopes from less ideal locations throughout the Northern Hemisphere.

Hartley 2's brightness, and its unusually fast slide across the constellations, both result from how closely it will approach Earth: by just 0.12 astronomical unit (11 million miles; 18 million km) on October 20th. This will be its closest approach since its 1986 discovery and one of the closest approaches of any comet in the last few centuries.

October 1st finds the comet passing 1.5° south of 2.2-magnitude Alpha Cassiopeiae, high in the northeast during moonless evenings.

On the night of October 7th in the Americas, when the comet should be 5th or 6th magnitude, it creeps less than 1° south of the Double Cluster in Perseus; the two clusters are magnitudes 4.3 and 4.4. This will make for a wonderful wide-field sight and a great astrophoto opportunity - particularly since it's new Moon!

From here on Hartley 2 turns southeast, passing near the head of Perseus. On October 20th the comet is closest to Earth, at a distance of 0.121 a.u. On that date the fuzzy visitor is passing just south of brilliant Capella.

By the end of October the comet should still be around 5th magnitude - but now in Gemini. So it doesn't gain a high altitude until later in the night. Perihelion, 1.06 a.u. from the Sun, comes on October 28th - but that morning the nearly last-quarter Moon is just a few degrees away.

NASA's Deep Impact/EPOXI spacecraft will fly by some 435 miles from Comet 103P/Hartley 2 on November 4, 2010.

Malcolm Hartley first spotted it on March 16, 1986. Hartley 2's next return was in 1991, when it brightened that September to 8th magnitude. It did so again at its following return in December 1997. The 2004 apparition was a poor one, with the comet far from Earth.

From Encounters with Comet Hartley 2, by Greg Bryant, Sky and Telescope, September 10, 2010

See Spaceweather.com.
See its orbit, ephemeris and orbital elements at 103P/Hartley 2 (JPL Small-Body Database Browser).

See Comet Snowstorm Engulfs Hartley 2 (Science@NASA, Nov. 18, 2010) [NASA - EPOXI Mission]


Jupiter and Uranus were in conjunction (some 0.81° apart) on September 18 '10.
They could be observed with binoculars or a small telescope, after sunset, above the eastern horizon, in Pisces. Jupiter (diameter 50") was a very bright Mag. -2.9, Uranus (diameter 4"), much dimmer, was Mag. 5.7 and 26' to the Northeast of Mars. Uranus rose at 19:26 and Jupiter at 19:28. The Sun set to the West at 19:21.
Jupiter and Uranus will continue to be close in the sky for months, as they move slowly across the firmament.
Calculations with TheSky from Software Bisque, version 6.


Mars and Uranus were in conjunction (some 0.43° apart) on April 15 '09.
They could be observed with binoculars or a small telescope, before sunrise, low above the Eastern horizon, some 8° to the South of Venus. Mars (diameter 4.38") was a bright Mag. 1.19, Uranus (diameter 3.34"), much dimmer, was Mag. 5.93 and 26' to the Northeast of Mars. Venus rose at 05:25, Uranus at 05:29 and Mars at 05:31. The Sun rose to the East at 06:57. Jupiter and Neptune rose earlier.
Calculations with TheSky from Software Bisque, version 5.


Comet 2007/N3 Lulin:
It is a non-periodic comet with a hyperbolic orbit (this will be its only visit to the Sun), discovered in 2007 by a Taiwan and Chinese group, it reached perihelium on March 24 '09 1.16 UA from Earth, in Gemini.
Quanzhi Ye, a student at China's Sun Yat-sen University, found Comet Lulin while examining images from the Lulin Observatory in Taiwan as part of an asteroid sky survey. See Yeiht (Quanzhi Ye).
On March 1 '09 it rose at 16:42 to the East-Northeast, observable with small telescopes or binoculars (it was at Mag. ~6), close to R.A. 9h 36m, Dec. 14° 0', 8° West of Regulus, in Leo, moving West and rising earlier every day.
Under dark skies it shows a green coma some 7' in diameter, a faint tail and an even fainter anti-tail.
On February 6 it was at R.A. 14h 52m, Dec. -15° 41', 25' North of Zubenelgenubi, in Libra, 0.78 A.U. from Earth.
On February 15 it was at R.A. 13h 31m, Dec. -8° 53', some 3° North of Spica, in Virgo, 0.53 A.U. from Earth.
On February 23 it was at R.A. 11h 21m, Dec. 4° 19', some 2° South of Saturn, in Leo, 0.41 A.U. from Earth.
On February 27 it was at R.A. 10h 9m, Dec. 11° 15', some 40' Southwest of Regulus, in Leo, 0.44 U.A. from Earth.

See Spaceweather.com (with Comet Lulin (C-2007 N3) photo gallery).
See Green Comet Approaches Earth (February 4 '09, Science@NASA),
with the sky charts for February 6 '09, February 16 '09 and February 24 '09.
See Sky Show This Month: "Two-Tailed" Comet Nearing Earth (National Geographic News).
See Comet Chasing (Gary Kronk, Cometography).
See its orbit, ephemeris and orbital elements at C/2007 N3 (Lulin) (JPL Small-Body Database Browser).

See Spectacular Photo-op on Saturn (Quadruple Transit of moons for February 24 '09, Science@NASA).


Saturn and Mars were in conjunction (some 0.65° apart) on July 10 '08; they were seen naked-eye, with binoculars or a small telescope, after sunset, less than 40° above the Western horizon, some 6° to the East of (above) Regulus (Alpha Leonis, Mag. 1.4). Saturn, the brighter, was Mag. 0.75, Mars was Mag. 1.68 and to the South of Saturn. Mars set at 22:57 and Saturn at 22:58. The Sun set on the North-North-West at 20:15.
The diameter of the Full Moon is some 0.5°.
Calculations with TheSky from Software Bisque, version 5.


Mercury and Venus in Conjunction on the Eastern sky:
On March 24, 2008, at 06:00, Mercury and Venus were visible some 58' apart, some 6° above the Eastern horizon. Venus (Mag. -3.9) rose at 05:27, then Mercury (Mag. -0.27) at 05:30. Sunrise was at 06:19. Both were be in the constellation of Acuarius. Uranus was some 5° to the East, rising at 05:40.
Calculations with TheSky from Software Bisque, version 5.


Venus and Jupiter in Conjunction on the Eastern sky:
On February 1, 2008, at 06:00, Venus and Jupiter were visible some 20° above the Southeastern horizon. Jupiter (Mag. -1.9) was some 35' South of Venus (Mag. -4) and somewhat lower, both in the constellation of Sagittarius. Venus rose at 05:02, Jupiter at 05:04. Sunrise was at 07:04. We recommended observing with a small telescope or binoculars.
Calculations with TheSky from Software Bisque, version 5.


SCAS scheduled a public Lunar Eclipse Watch at Bill Sadowski Park on February 20 '08 from 8 to 11 PM.

Total Eclipse of the Moon: (in Leo)

                      Bill Sadowski Park    Key Biscayne Beach Park
                     W 80° 19', N 25° 37'     W 80° 09', N 25° 41'

                       Eastern Standard Time      Moon's
                                     h  m    Azimuth°  Altitude°
Moonrise               2008 Feb 20  18:04       77.3   ----
Moon enters penumbra   2008 Feb 20  19:34.9     86.7   18.7
Moon enters umbra      2008 Feb 20  20:43.0     94.2   33.5  <-- Visible eclipse started
Moon enters totality   2008 Feb 20  22:00.5    105.5   50.2
Middle of eclipse      2008 Feb 20  22:26.0    110.6   55.6  <-- Darkest eclipse
Moon leaves totality   2008 Feb 20  22:51.5    117.2   60.7
Moon leaves umbra      2008 Feb 21  00:09.1    155.3   72.8  <-- Visible eclipse ended
Moon leaves penumbra   2008 Feb 21  01:17.2    211.1   71.5
Moonset                2008 Feb 21  07:06      279.2   ----
Eclipse Predictions by Fred Espenak, NASA's GSFC

This eclipse was visible in the Central Pacific Ocean, America, Europe and Africa. The eclipse was darker to the North of the Moon because it passed South of the center of the umbra projected by the Earth.
Saturn was less than 5° East of the Moon. Regulus (Alpha Leonis) was less than 2° West of the Moon.

For the exact times at your locality, you can use the USNO Eclipse Portal at the U.S. Naval Observatory.
For more information and graphics, see NASA - Total Lunar Eclipse February 20, 2008, Fred Espenak, NASA/GSFC.




Notes:   (A glossary of important terms for the sky observer)


The Speed of Light (and of any electromagnetic wave) in a vacuum (c), is 299,792,458 m/s, about 300,000 Km/s.

1 Astronomical Unit (A.U.) is the average distance between the Earth and the Sun, 149,597,870.691 Km, about 150 million Km, and light takes 8 minutes 19 seconds to traverse it.

Since Velocity = Space / Time, the delay to receive information via electromagnetic waves from a given distance is:
Time (sec.) = Distance (A.U.) / c (A.U./sec) = 499,005 x Distance (A.U.)
This causes that when observing a celestial object, we see it as it was in the past.

1 Light-Year is the distance that light travels in free space during a year, 63,239.85831 A.U., about 9.5 trillion Kilometers.

1 parsec (pc) is the distance at which the Stellar Parallax is equal to 1".
1 parsec = 3.262 light-years = 206,265 A.U. = 3.086 x 1013 Km.

Stellar Parallax is the apparent shift in the position of a relatively nearby star, when this is determined (with respect to the distant stars) from the ends of a baseline of 1 A.U. (positions taken 6 months apart show twice the Parallax).

The Apparent Magnitude is a measure of the observed brightness of a celestial object. It is equal to the Visual magnitude (V). Brighter objects have smaller magnitudes; The more briliant an object is, the smaller its magnitude. One unit of magnitude equals to 2.512 times brighter. The brightest objects are: the Sun (Mag. -26.7), Full Moon (Mag. -12.6), Venus (Mag. min -4.7), Sirius (Mag. -1.44), Canopus (Mag. -0.62), Alpha Centauri (Mag. -0.27), and Arcturus (Mag. -0.05). On a clear night the naked eye can see stars to Mag. 6.5.

The Absolute Magnitude is a measure of the true brightness of a celestial object. It is equal to the apparent magnitude at a distance of 10 parsecs of the object.

To measure approximately 10° of sky, use the width of your fist at arm's length. 2° of sky roughly correspond to the width of your index finger, at arm's length. The Moon and the Sun, have approximately 0.5°, about 30' of diameter (° = degrees, ' = minutes of arc).

The sky moves 15° towards the West each hour due to the Earth's rotation (which is from the West to the East). This would allow us to observe, on any night of the year, almost all of the firmament (360°), if we could observe it for 12 hours, say from 18:30 towards the western horizon until 06:30 towards the eastern horizon. The illumination after sunset and before sunrise, reduces this to about 330°, and considerations about the desired height above the horizon for a good observation of a star reduce it even more. Note that every 6 hours the sky moves 90° towards the West.

The sky moves westward about 1° each day, due to the Earth's translation (which is from the West to the East). This causes a certain star to appear on the horizon in the East about 4 minutes earlier every day. For this reason, the sky we see today at 10 pm, we'll see next month at 8 pm. In this way, during the course of a year, we will see all the stars fixed in the firmament (360°) Culminate, if you look every day at the same time. Note that during each of the 4 seasons of the year the sky moves 90° towards the West.

It is said that a celestial object is at Culmination, when it crosses the Local Celestial Meridian (North-South maximum circle in the sky that passes through the Zenith).

A Sidereal Day (23h 56m 4.1s) is the period of rotation of the Earth with respect to the stars.

The Sidereal Period is the time that it takes a planet to complete one orbit around the Sun, measured in relation to the stars.
[See Solar System Data in ARVAL]

The Synodic Period is the time that it takes a planet to complete one orbit around the Sun, measured relative to the Earth. It is the time that it takes a planet to complete a cycle of phases, the time interval between two successive equal phases.
[See Solar System Data in ARVAL]

It is said that a celestial object is in Opposition, when it is opposite to the Sun in the sky and Culminates at midnight, rises at dusk and sets at dawn. This takes place annually for fixed celestial objects, and once in each Synodic Period for an exterior planet. An exterior planet (Mars, Jupiter, Saturn, etc.) will then be close to its smaller distance to the Earth for that period, with 100% phase.
The Opposition will be Aphelic when the planet is near its Aphelion, Perihelic when it is near its Perihelion.
The best conditions of observation for a planet happen before its Opposition until somewhat later.

It is said that a body in the Solar system is in Conjunction with another, when they are lined up in space, from the point of view of the Earth. They have equal Right Ascension and their Declinations are very close in the sky.
A Solar Conjunction occurs once in each Synodic Period for an Exterior Planet (Mars, Jupiter, Saturn, Uranus, Neptune and Pluto), which will then be at its greatest distance from the Earth for that period. Its phase will be 100%, and its observation will be impeded by the brightness of the Sun.
For an Interior Planet (Mercury and Venus), we talk about a Superior Conjunction, when it is behind the Sun, going from West to East (in Direct Motion). We talk of an Inferior Conjunction, when it is between the Earth and the Sun, going from East to West (in Retrograde Motion). A Transit would occur if they also had the same Declination (as an Orbital Node of the planet passes in front of the Sun).
For an Exterior Planet (Mars, Jupiter, Saturn, Uranus, Neptune and Pluto), we talk about a Solar Conjunction when it is behind the Sun, going from West to East.

After a Solar Conjunction, an Exterior planet will be visible on the eastern horizon, before dawn.
After an Inferior Conjunction, an Interior Planet will be visible on the eastern horizon, before dawn.
After a Superior Conjunction, an Interior Planet will be visible on the western horizon, after sunset.
Before a Solar Conjunction, an Exterior Planet is visible on the western horizon, after sunset.
Before an Inferior Conjunction, an Interior Planet is visible on the western horizon, after sunset.
Before a Superior Conjunction, an Interior Planet is visible on the eastern horizon, before dawn.

The Right Ascension (R.A.) on the celestial sphere is equivalent to the Longitude on the Earth.
Instead of 360° to cover the full sphere, we use 24 hours. 1 hour of R.A. = 15° in the Celestial Sphere.
The Right Ascension (R.A.) increases for the stars more eastward in the Celestial Sphere, that rise later.
The term "Right Ascension" comes from the fact that, when observed from a Latitude equal to their Declination, all the stars rise (ascend) at a right angle to the horizon. So their positions, in Sidereal Time, are called hours of Right Ascension.
The meridian of 0 hours of R.A. passes through the Vernal Equinox, currently in the constellation of Pisces, having been displaced from Aries in the past 2,000 years, due to movement of Precession of the Earth's axis (about 1.4° per century).

The Parallels of Declination (Dec.) in the Celestial Sphere are equivalent to the Latitude on Earth. In the same way, ranging from -90° in the Celestial South Pole, up to +90° at the Celestial North Pole, passing through the Celestial Equator, at 0°.

The Celestial Poles are the points where the axis of rotation of the Earth intersects the Celestial Sphere. The Celestial North Pole is currently 0.7° North of the Star Polaris, at the end of the tail of the constellation Ursa Minor (Little Bear), in R.A. 2h 34', Dec. 89° 17' N. Its height above the horizon is approximately equal to the latitude of the place of observation.
The Celestial South Pole is currently in the constellation Octans, without a nearby star.

In their movement of Precession the Celestial Poles describe circles in the sky with a radius of 23.5° and a period of ~25,800 years. This causes an increase in the R.A. of a star of about 1' every 20 years.
Precession is the periodic conical motion of the axis of rotation of a body, as a result of the inclination of this axis. The Terrestrial axis Precession causes the displacement toward the West of the equinoxes (the nodes of the ecliptic) at an average of about 50.27" per year, and also the stars nearest to the Celestial Pole change cyclically.
Currently, the Earth is closer to the Sun in January and farthest in July.
The Inclination of the Earth axis is currently 23.5°, but in a cycle of ~41,000 years varies from 22.1° to 24.5°.

The Celestial Equator (Dec. 0°) is the intersection of the plane of the Earth's Equator with the Celestial Sphere, the sky. The Celestial Equator intersects the horizon at points directly to the East and West, in any place on Earth. And its inclination to the South (at Lat. North) or North (at Lat. South), is equal to the Latitude of the place. During a night all the stars describe in the sky arches parallel to the Celestial Equator.

Regarding these Equatorial Coordinates, Right Ascension and Declination, it is said that the stars are fixed in the sky, constituting the firmament. Also with regard to them, it is said that the Planets, the Sun and Moon move in the sky. But the set of all the stars in the sky moves slightly in the sky due to the Movement of Precession of the Terrestrial axis, as well as an annual Parallax caused by the movement of the Earth in its orbit around the Sun. Even more slightly they move individually (Proper Motion) because of the movement of the Sun and of each star in the Milky Way.

The system of Terrestrial Coordinates (Alt-Az) measures the height above the horizon and the Azimuth to the right of the North (both angles are measured in degrees). The Zenith is the point directly above the observer, at 90° of Altitude.

The Ecliptic is the intersection in the sky, between the plane of orbit of the Earth and the celestial vault, where the stars seem to be fixed. It is the path of the Sun in the sky, near which the planets move without much deviation (except Pluto).
The Nodes in the orbit of a planet are the two points where it crosses the plane of the Ecliptic.

The Equinoxes are the two points of intersection between the Ecliptic and the Celestial Equator. They are the two times of the year when the center of the Solar disk is exactly over the Celestial Equator (Dec. 0°). The Sun culminates vertically on the Terrestrial Equator (Lat. 0°) in these two days.
The Vernal Equinox, which marks the beginning of spring in the northern hemisphere, and the beginning of autumn in the South, takes place close to March 21, with the Sun in Pisces. The Sun will have a northern declination to the autumnal Equinox. The Vernal Equinox is also the point of 0h 0m of Right Ascension.
The Autumn Equinox, which marks the start of autumn in the northern hemisphere, and the beginning of spring in the south, takes place near September 23, with the Sun in Virgo. The Sun will have a southern declination until the Vernal Equinox. The autumnal Equinox is also the point of Right Ascension 12h 0m.
But the day and night are not the same length on the Equinoxes, this occurs, for the latitudes close to 5° N, near February 25 and October 15, due to the atmospheric refraction (which lengthens the days shortening nights).
[See the RGO Leaflets - The Equation of Time in ARVAL].
[See Equinoxes at the U.S. Naval Observatory].
[See Fall Equinox (Starman by Jay Ryan) in ARVAL].

The Solstices are the two points where the Sun reaches its maximum distance (Declination) off the Celestial Equator. The Summer Solstice marks the longest day of the year, and the Winter Solstice, the longest night.
The Summer Solstice for the northern hemisphere, and Winter Solstice for the southern hemisphere, takes place near June 21, when the Sun reaches its maximum North Declination (about 23.5° N), in Taurus, with a R.A. of 6h. The Sun culminates vertically on the Tropic of Cancer (Lat. 23.5° N) on this day, the beginning of Summer in the northern hemisphere and of Winter in the South.
The Winter Solstice for the northern hemisphere, and the Summer Solstice for the southern hemisphere, occurs about December 22, when the Sun reaches its maximum South Declination (about 23.5° S) in Sagittarius, with R.A. of 18h. The Sun culminates vertically on the Tropic of Capricorn (Lat. 23.5° S) on this day, the beginning of Summer in the southern hemisphere and of Winter in the North.
[See the RGO Leaflets - The Equation of Time in ARVAL].
[See Sunrise and Sunset Times Near the Solstices at the U.S. Naval Observatory].
[See Winter Solstice (Starman by Jay Ryan) in ARVAL].
[See Summer Solstice (Starman by Jay Ryan) in ARVAL].

The Interquartiles ("Cross-Quarter Points") are the midpoints between an Equinox and a Solstice. They are the centers of the seasons of the year. They are conventionally on February 4, May 6, August 8, and November 7.

The Terrestrial Apex is the direction at a given time, of the orbital movement (translation) of our planet around the Sun. The Terrestrial Apex is always 90° to the West of the Sun on the Ecliptic plane, rises at midnight and culminates at dawn.
A region of the Earth is favored for the maximum of a meteor shower, when the Terrestrial Apex is near the radiant in the sky for an observer in that region.

The Zodiac is the area of the sky 8° on either side of the Ecliptic. The path in the sky of the Sun, the Moon and the planets remain within this area, all normally moving eastward (Direct Motion).
Occasionally, a planet presents movement toward the West (Apparent Retrograde Motion).
In the case of an Exterior Planet (Mars, Jupiter, Saturn, Uranus, Neptune and Pluto), Retrograde Motion is due to the effect of parallax when the Earth reaches it and passes it. In the case of an Interior Planet (Mercury and Venus), Retrograde Motion is due to the effect of parallax, when being on the same side of the Sun to the Earth, the planet reaches it and passes it.
The change of Direct Movement to Retrograde, combined with the inclination of their orbits, causes the planets to make loops in the sky. These loops occur in each Sidereal Period for the Interior Planets, in each Synodic Period for the Exterior Planets.
[See Loops in the Sky: The Movement of the Planets, in ARVAL]

Aphelion is the point in the orbit of a planet, with greater distance to the Sun.
Perihelion is the point in the orbit of a planet, with less distance to the Sun.
Apogee is the point in the orbit of a satellite, with greater distance to the Earth.
Perigee is the point in the orbit of a satellite, with less distance to the Earth.

The Longitude on Earth is related to the Local time;
360° of Longitude equals 24 hours, i.e.: 1° of Longitude is equivalent to 4 minutes, 1' of Longitude to 4 seconds.
1 second is equal to 0.25" of Longitude, 1 minute is equivalent to 15' of Longitude, and 1 hour to 15° of Longitude.
The sky moves 15° towards the West each hour due to the rotation of the Earth.

Eastern Standard Time (UT - 5 hrs.) in the USA is equivalent to 75° W of Longitude and the East Coast is near this Meridian.
For Miami, FL (80° W) the legal time is 20 minutes behind of the astronomical Local Time.

About the Equator, 1' of Longitude is equivalent to 1 NM (Nautical Mile) = 1.852 Km, and 1° of Longitude is equivalent to 60 NM = 111.12 Km. The Terrestrial Circumference is 360 x 60 = 21,600 NM = 40,003.2 Km.
The Earth is not a perfect sphere: geographically the Earth Equatorial circumference is 40,076.5 Km, and the Polar circumference is 40,008.6 Km. Its Polar diameter (12,713.54 Km) is 42.8 Km smaller than its equatorial diameter (12,756.34 Km): 0.34% lower.
1' of Latitude always equals 1 NM = 1.852 Km and 1° of Latitude is 60 NM = 111.12 Km.

At Civil dawn or dusk the Sun has an Altitude of -6°, at Nautical -12°, at Astronomical -18°.
Civil refers to the lighting of objects on the outdoors, Nautical to the horizon, Astronomical to the sky.




The Moon orbits the Earth at an average distance of 384,401 Km, at Perigee it can reach 356,375 Km, at Apogee 406,720 Km.
See Inconstant Moon (John Walker, Fourmilab).
The Moon has an area of 37.96 million Km2, a diameter of 3,476 Km, and a mass 0.01230 times that of the Earth.
From Earth, the average angular diameter of the Moon is 2*atan((3,476/2)/384,401) = 0.518° = 31.1'.
At Perigee, the angular diameter of the Moon is 33.5', at Apogee 29.4' (a 12.3% difference).

The main effect of the Moon on the Earth are the tides, caused by their gravitational attraction.
See The Tides ("RGO Leaflets, in ARVAL).

The Moon has a diameter close to 31'. Its maximum magnitude is close to -12.6. It rises and sets some 53 minutes later each day. Its phases are repeated every 29.53 days approximately, this is its Synodic Period, the Lunar "day". The Moon is one of the most satisfying celestial objects to observe with a small telescope or binoculars.
You can orient on it with the Observatorio ARVAL - Moon Map.

"Earthshine", the Brightness from the Earth, whose clouds reflect the Solar light illuminating the dark area of the Moon, is stronger in the months of April and May. The phenomenon is most noticeable near the New Moon. Best viewed towards the East, before dawn, in the days before the New Moon, and to the West, after sunset, in the days after.
See The Da Vinci Glow (NASA Science. October 4, 2005)

The period of rotation of the Moon is equal to its period of translation: 27.32166 days with respect to the stars.
This causes the Earth to always see the same side of the Moon.

The Librations are periodic movements of a body in its orbit.
The various Librations of the Moon allow to observe from the Earth up to 59% of its surface.
The Libration in Latitude, a North-South swing of about 5.13° on average, is caused by the tilt of its axis of rotation relative to its orbital plane, and the disturbances caused by the Sun can add or subtract up to 0.9°.
The Libration in Longitude comes from the difference between its variable orbital velocity and constant rotation speed, and with no other factors the swing would be on average of about 6.29°, but the contribution of the Sun takes its maximum to 7.75°.
There is also a Optical Diurnal Libration of less than 1°, that comes from that due to the rotation of the Earth, we see the Moon from slightly different angles at dawn and dusk. This is because the Moon is locked in synchronous rotation with the Earth.

The inclination of the axis of rotation of the Moon, relative to its orbital plane, is 6.7°.
The inclination of the Lunar Equator (and the Moon's orbital plane) with respect to the Ecliptic varies between 18.3° and 28.6°.
The maximum Declination of the Moon is ±28.6° and their maximum separation from the Ecliptic is 5.1°.

The orbital period of the Moon around the Earth, with respect to the stars, is 27.32166 days, this is its Sidereal Period, but with respect to the Earth it is 29.53059 days, the interval between two successive equal phases, this is its Synodic Period, the Moon "day", during which the Moon crosses the ecliptic 2 times; in the Nodes of its orbit.

The movement of translation of the Moon, is from the West to the East, and only appears otherwise because it is slower than the movement of rotation of the Earth (also from the West to the East), that "leaves it behind".

The Terminator is the boundary between the illuminated and the dark areas of the Moon, and always moves from the West to the East, seen from the Earth. But from the point of view of the Moon, with its own geographic directions, where East and West are opposite to those allocated observing from the Earth, the Terminator advances from the East, where the Sun rises, as on Earth.

Although the Full Moon occurs every month in a specific date and time, the disc of the Moon can appear filled for several nights in a row. This is because the percentage of the disk of the Moon that appears illuminated changes very slowly near the time of Full Moon.

Elongation is the angular distance to the Sun measured along the Ecliptic, East for objects visible after sunset, West for objects visible before dawn.

The Ecliptic is the intersection in the sky, of the plane of orbit of the Earth with the celestial vault, in which the fixed stars seem to be. It is the path of the Sun in the sky, near which the planets move without much deviation (except Pluto).
The Nodes in the orbit of a planet are the two points where it crosses the plane of the Ecliptic.

A Solar Eclipse can only occur on a New Moon, and a Moon Eclipse on a Full Moon, if the Moon at that time is in one of its Nodes, passing through the Ecliptic, the plane of the Earth's orbit.




This page was updated in: July 24 '14

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