The Solar System
has nine planets that orbit the big star called the Sun. All
the planets orbit the Sun in elliptical paths. They take different
amounts of time to get all the way around the Sun. Our Earth
takes a year to make one complete orbit. This is the length of
time it takes the Earth to get all the way around the Sun.
Many ancient
civilisations worshipped the Sun as a god. In Egypt is was Ra, in
Greece Helios and in Ancient Rome, Helios. The Celts had Lugh, the
Aztecs had Tonatiuh and the Japanese believed in Amaterasu, the Sun
Goddess...
Luna to the Romans, Selene and Artemis
by the Greeks. Phoebe, Diana, Artemis, Luna, Serenity, Usagi, Serena
are the names of women connected with the Moon. Known since prehistoric
times. It is the second brightest object in the sky after the Sun.
Orbits around Earth every 29.5 days (709 hours)...
Mercury's orbit is highly
eccentric. Its surface is very old and heavily cratered. Mercury
is the second densest major body in the solar system, after Earth.
It has a massive iron core and a relatively thin silicate outer shell.
Mercury has a very thin atmosphere which is constantly shifted by
solar winds.
The pressure of Venus' atmosphere at
the surface is 90 atmospheres (about the same as the pressure at
a depth of 1 km in Earth's oceans). It is composed mostly of carbon
dioxide. There are several layers of clouds many kilometres thick
composed of sulfuric acid. These clouds completely obscure our view
of the surface. This dense atmosphere produces a greenhouse effect
that makes Venus' surface temperature hotter than Mercury's despite
being nearly twice as far from the Sun.
In common with the entire solar system, the earth is
moving through space at the rate of approximately 20.1 km/sec or 72,360
km/h (approximately 12.5 mi/sec or 45,000 mph) toward the constellation
of Hercules. The Milky Way galaxy as a whole, however, is ..
Mars has a very thin atmosphere composed
mostly of the tiny amount of remaining carbon dioxide (95.3%) plus
nitrogen (2.7%),
argon (1.6%) and traces of oxygen (0.15%) and wa..
The gas planets do not have solid surfaces, their gaseous
material simply gets denser with depth (the radii and diameters quoted
for the planets are for levels correspondin.
