Observatorio ARVAL

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Basic Visual Astronomy

The day sky (the Sun and Moon) and the night sky (stars and planets), as shown by Stellarium.
- Out of 180° of sky; fist of extended arm = ~10°, index of extended arm = ~2°, Sun and Moon = ~0.5°.
- For observers North of the Equator, the sky "revolves" around an axis from the Earth to 0.7° north of Polaris,
  the "North Star". Stars, planets, the Sun and Moon, rise in the Eastern horizon and set in the Western horizon.
- The sky "moves" ~15° to the West in one hour due to the rotation of the Earth,
  and ~1° to the West in one day due to its orbital revolution (a star is ~4 min. earlier every day).
- Earth's sidereal period is 365.2422 days = 1 year. Earth's sidereal day is 23h 56m 4s.
- The Sun drifts Eastward in the sky ~1° per day along the Ecliptic.
- The planets drift Eastward (prograde) in the sky along the Zodiacal band, 8° to each side of the Ecliptic,
  but will drift Westwards (retrograde) as an interior planet passes the Earth,
  or as an exterior planet is passed by the Earth.
- The Moon drifts Eastward in the sky along the Ecliptic ~13° per day (it is ~53 min. later every day),
  but appears to move Westward because the rotation of the Earth (Eastward) is faster.
- The Moon's rotation period is equal to its translation period = 27.32166 days,
  thus always showing the same side towards the Earth.
- The Moon's synodic period is 29.53 days = 1 Lunar day:
  the Full Moon rises at sunset, the Waning Last Quarter Moon at Midnight,
  the New Moon at dawn, and the Waxing First Quarter Moon at noon.


The Moon is one of the most satisfactory celestial objects to observe with binoculars or a small telescope.

Mercury, Venus, Mars, Jupiter and Saturn are generally visible without instruments;
   they look like very bright stars, but with a more stable light than the stars.
   A small telescope can show details in them.
   Occasionally Uranus and the dwarf planet 4 Vesta can be seen also without instruments.

It is possible to observe meteors streaking a few times during a dark night,
   these interplanetary grains of dust burn out high in the atmosphere.
   On rare occasions a comet will be visible moving very slowly against the stars.
   Satellites, illuminated by the Sun, can be seen moving rapidly after sunset or before dawn.


On a dark night, the disk of our galaxy, the Milky Way, can be seen shinning like an illuminated cloud on the constellation Sagittarius (where it is brightest, toward the center), and circling trough Scorpius, Ophiuchus, Centaurus, Crux, Carina, Canis Major, Orion, Auriga, Perseus, Cassiopeia, Signus, and Aquila.
The Solar System must be near the plane of our galaxy for the Milky Way to divide the sky in two almost equal parts.


See also:
- The Sky of Miami, Florida (Sky and Telescope Interactive Sky Chart, Java applet)
- Heavens-Above (Miami, Sky Chart)
- Heavens-Above (Miami, Planets Summary)
- Heavens-Above (Main Page; visibility of the sky and satellites for Miami)
- Weather Underground Sky - Miami (The sky visible from Miami)
[Configurable for any place and time]


ARVAL - References:
- Moon Map
- Solar System Data
- Classic Satellites of the Solar System
- Loops in the Sky: The Movement of the Planets
- Luminic Map of Florida
- Astrophotography with the Meade LPI Digital Camera
- Astrophotography with the Meade 127ED APO Refractor and the Canon EOS 10D DSLR
- RGO Leaflets: The Tides, Orbits, Eclipses, Comets, Meteors and Meteorites,
  What is a Star?, Supernovae, Telescopes, Galaxies
- Meteorology for South Florida and the Caribbean




To observe the Moon, the planets (and more) with our telescopes, come to the Southern Cross Astronomical Society (SCAS) free public observation sessions "Saturday Nite Live Astros", from 8 to 10 PM, at Bill Sadowski Park (Miami-Dade), SW 176th St/SW 79th Ave (1/2 mile west of Old Cutler Road).
No car lights, lasers, white light flashlights, litter, loud noise, alcohol or pets.

To observe the Sun with our telescope and Hydrogen-Alpha filter, come to the Southern Cross Astronomical Society (SCAS) free public Solar observation sessions, Saturdays from 10 AM to noon, at the Miami MetroZoo, 12400 SW 152nd Street (Coral Reef Drive, 3 miles west of I-95, Enter the MetroZoo on the left at SW 124 Avenue).

See the National Weather Service Forecast - Miami, FL before leaving home. Call the SCAS Hotline at 305-661-1375.



This page was updated in: May 15 '07, July 3 '13

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Spanish: Astronomía Visual Básica (Rojo y Negro)

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