Appearance: A 0.5-wide bright disk; Apparently smooth and uniform, during eclipses shows an "atmosphere"; Upon closer inspection *and using the right kind of light) it shows sunspots and other
What is it? From its spect
Phases & Eclipses
Motion and Phases of the Moon
Orbit: The Moon revolves the Earth with a prograde orbit, with period (sidereal month) 27.3 days [it covers 12/day, almost 1 km/sec],
tilted 5; It is not exactly a circle [the distance can be measured to
First telescopes: 1608 in the Netherlands, magnified 2-3 times objects on land; spread quickly and were available in Italy by 1609.
First use in astronomy: Galileo improved the design in 1609 until it
magnified 20, then turned it to t
Solar System 1
Overall properties: The name comes from the king of the gods,
Zeus / Jupiter; The planet's radius is 11.2 Earth radii, with a rotation period 10 hr, and the radius of its orbit is 5.20 AU [with a period 11.9 years]; It is more mass
Solar System 2
Overall properties: The name comes from the God of the Heavens,
father of Cronus-Saturn [+ Cyclopes + Titans]; Almost 20 AU from
the Sun, on an almost circular orbit [eccentricity 0.02, period 84
years]; The planet is a bluish gas b
History of Astronomy
Prehistoric Period - Early Sites and Archeoastronomy
Earliest evidence: Cave paintings like the ones at Lascaux (16,000 yr
old) and others including depictions of celestial objects (stars,
5000-yr old map of the Moon).
Life in the Universe
What Happened on Earth?
4.6 Gyr ago: Formation of the Earth.
4.5-4 Gyr ago: Chemical evolution: - At first, atmosphere formed
from H, N, C, O degassing; Then, those gases combined into CH ,
NH , CO , H O molecules.
3.9 Gyr ago: Hea
Meteors or "shooting stars": Small grains, at most pea-sized (not
stars at all!) that crash into our atmosphere at 160,000 mph [compared to 2,230 mph for a rifle bullet]; Millions burn up every day
several tens of miles up in our
The Celestial Sphere
What is it? An imaginary sphere surrounding the Earth on which celestial objects appear to be located; thought to really exist in antiquity, today used as tool to identify locations in the sky.
Special places: Celestial Equator, Nor
Star Patterns in the Sky
What are they? 88 currently recognized patterns [There used to be
other ones, no longer officially recognized, like the XIX century
Quadrans Muralis, after which the Quadrantid meteor shower is
named, or the Pleiad