EARTH and the MOON


Equatiorial Radius6,378.140 km
Mean Density5.515 g/cm³
Sidereal Rotation23h56m0.41s
Sidereal Period365.26

The third rock from the Sun. Earth is our home planet. It is the only planet in the solar system that has liquid water and the only planet (we know so far) that has intelligent(?) life.
The structure of Earth is made up of layers. The inner core is made up of iron and nickel. The very center is probably solid, but the outer part of the core is probably a dense liquid. The next layer out is called the mantle. The mantle is the largest, or thickest area of the planet. The final layer is the crust. The Earth's atmosphere is also layered. There are 5 layers: Ionosphere (90 KM up and 350 KM thick), Mesosphere (50 KM up and 40 KM thick), Stratosphere (18 KM up and 30 KM thick), Tropopause (14 KM up and 4 KM thick), and, Troposphere (Ground level to 14 KM up).
Information regarding the Earth falls more into the category of geology so I will leave the rest of the explanations up to the geologists.
Moon lineThe MOON is the Earth's satellite. It revolves around the Earth once every 27 days, 7 hours and 43 minutes. The Moon's diameter is 3476 KM (2159 miles). The Moon is EASILY viewed, studied, drawn, and photographed. You don't even need binoculars or a telescope to start, just your eyes! The Moon has one side that always faces the Earth. The other side, or dark side as some call it, is NOT always dark! When the Moon is between the Sun and the Earth, the back side of the Moon is facing directly towards the Sun.

For some reason, the back side of the Moon is by no means as interesting as the side that faces us. The craters on the back side are much smaller and less spectacular. Let's break the side that faces us into 2 sections:

Part #1 - The section we see from new to full:

Moon right
  1. Mare Crisium (Sea of Crisis)
  2. Mare Fecunditatis (Sea of Fertility)
  3. Mare Nectaris (Sea of Nectar)
  4. Mare Tranquillitatis (Sea of Tranquility)
  5. Mare Serenitatis (Sea of Serenity)
  6. Mare Vaporum (Sea of Vapours)
  7. Mare Australe (Southern Sea)
  8. Mare Frigoris (Sea of Cold)
Upon examining the Mare listed above, you will notice there are a lot of impact craters. These craters also have names, but there are just so many of them, that it wouldn't make sense to list them all here. If I have enough requests, I might add a page of just the impact craters.

Part #2: The section we see from full back to new.

Moon left
  1. Mare Imbrium (Sea of Rains)
  2. Oceanus Procellarium (Ocean of Storms)
  3. Mare Humorum (Sea of Moisture)
  4. Mare Nubium (Sea of Clouds)
  5. Mare Cognitum (Known Sea)
  6. Tycho - Large Impact Crater with huge ejector
  7. Copernicus - Large Impact Crater highly reflective
I have mentioned two craters in this area because these are easily seen in binoculars or even with the naked eye. Many of the craters are named after famous people, not just astronomers.

Tips for Lunar Observing

When observing the Moon, it's best to start observing when the Moon is just coming out of the "new" phase and becoming a crescent. You should try and at least catch a glimpse of the Moon every night until the Moon becomes "full" which will be about 14 days. If you are viewing the Moon with the aid of binoculars or a telescope, you can spend hours just viewing along the terminator.

Moon Phase The terminator is the line where the light stops and the shadows of the lunar darkness begin. Along this line is where you can see the most amount of detail in the edge of the craters, the mountains, and the rilles. Aim your scope or binoculars to the top of the Moon and work your way down the terminator. Do this each night and you will see more and more and more every night. Keep notes if you wish, about the different features you notice. You may even want to draw the features as you see them.

MoonDON'T try and view the Moon when it is full. This is when the least number of features are clearly visible and the light from the full Moon coming through your binoculars or an unfiltered telescope can actually make you eyes ache! The Moon only reflects about 5% of the light it receives, but the light from the Moon can easily cast a shadow!

Moon PhaseAfter the Moon has past the "full" phase, the light will begin to recede leaving more details to see from a different angle. This time, the light will be coming from the east side of the Moon, causing the shadows to be cast in the opposite direction than when the Moon was going from "new" to "full". You will see the same features, just with a different perspective. This time, viewing the Moon will be a little more difficult. See, the Moon at last quarter won't rise until midnight and the crescent Moon won't rise until nearly 3:00am! This makes it more of a challenge (yeah right!)