Glossary of earth science ch. 27

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into what two groups are the planets divided?
the inner planets and the outer planets
what are the main characteristics of each group?
the inner planets are warmer than the outer planets
why does mercury have no atmosphere?
because it has a weak gravity which prevents it from retaining an atmosphere
why is the surface of venus so hot?
because about 80% of it is covered with lava
why does mars have no seasons?
because of the water there
why dies neither venus or mercury appear high in the night sky?
because they're far away because they are in the outer planets and earth is a part of the inner planets
why is it more likely that life existed on mars billions of years ago rather than it does now
because that was before the atmosphere thinned and the surface water froze
Which two planets have retrograde motion?
Venus and Mercury
Compare and contrast Earth and Venus
Earth:magnetic field/Venus:no
Both: density, mass, gravity is similar
Compare and contrast Uranus and Neptune
Uranus and Neptune not large enough to compress hydrogen into metallic state. Instead they have dense interior of water, methane and ammonia.
Both are tipped on their sides
Compare and contrast Terrestrial and Jovian planets
1. Jovian are much larger
2. do not have solid surfaces; have gas layer
3. composed mostly of light elements hydrogen and helium; terrestrail planets are made of heavier iron, silicon, oxygen, etc.
4. Terrestrial planets only have two moons in all but all Jovian planets have moons.
Why do Saturn and Jupiter radiate twice as much heat back to space as they receive from the sun?
They have their own source of internal heat - from original formation and from contraction due to gravity.
Why doesn't earth have a hydrogen-helium rich atmosphere like the Jovian planets?
Because we are closer to the sun.
What is the evidence Mars being solid, having water or the ability to do work?
It has polar ice caps that expand in winter and shrink in summer;
Mars has gravity (2 fifths of Earth's)
Describe the seasons if Earth was in Uranus' ortial plane.
Uranus is tipped on its side, so if Earth was tipped on its side our eastern and western hemispheres would have opposite seasons instead of our northern and southern hemispheres. When it was winter in the US, it would be summer in China.
Which planets are closest and farthest from the sun?
Mercury is closest.
Pluto is farthest.
Which planet is largest? Which is smallest?
Jupiter is largest, Pluto is smallest.
Why are the out planets called gas giants?
Because they are made up of gaseous layers, mostly hydrogen.
What characteristics of Earth make it capable of supporting life?
Atmosphere, water and carbon.
What are comets?
Dirty snowballs: dust particles trapped in a mix of frozen water, carbon dioxide, methane and ammonia. Spend most of their time beyond Neptune but sometimes move closer to the sun.
What are asteroids?
Solid rock-like objects, irregular shapes - may be left over from the solar system's formation.
Metgeors and Meteroroids
a rock or an icy fragment traveling in space. Same as asteroids only smaller. A meteor, (a shooting star) is the light from a meteoroid whewn it passes through the Earth's atmosphere. When the earth croses the paths of comets, meteor showers occur.

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