Earth’s Near Neighbors: Mercury, Venus, and Mars

Mercury

Mercury

• A large ball of iron with a thin layer of rock on top, rather than being mostly made of rock like Earth.

• The metal core is at least partially molten and extends 85% of the way to the surface.

Caloris Basin

The largest crater on Mercury.

MErcury Surface, Space ENvironment, GEochemistry, and Ranging.

MESSENGER

molten state

The crust of Mercury probably shrank as it cooled from a ____, which led to the ridges.

8 miles

Mercury’s diameter could have decreased by as much as _____.

Strong seismic

_____ waves from the collision that created Caloris must have passed through Mercury and around its surface before convergent at the antipode with disastrous results.

100 times

Earth's magnetic field is _____ stronger than Mercury's.

Ice

____ can be found at the bottoms of craters near Mercury's North Pole, which are always in shadow and extremely cold.

Venus

It is the hottest planet in the solar system, with a surface temperature of 870°F (465.5°C) that is relatively constant from the equator to the pole, day and night.

greenhouse effect

Venus has a high average temperature as a result of an extreme ____.

Virga

Rain that evaporates before it hits the ground.

Rilles

The winding canyons left by lava flows.

Baltis Vallis

This region contains the solar system's longest known rille, which spans Venus at a distance of about 4,230 miles.

aerodynamic forces

Objects capable of creating craters up to 2 miles in diameter are hindered and destroyed by ______ in Venus' thick atmosphere.

Venus Express

The European Space Agency probe that arrived at Venus in April 2006 and orbited it until May 2014.

Mars Global Surveyor

A satellite that operated in orbit around Mars from 1997 to 2006.

Laser Altimeter

An instrument that bounced pulses of light off the Mars surface to measure the altitudes of the surface features that reflected the light.

Mars Odyssey

NASA’s probe began orbiting Mars in October 2001. It has found caves and evidence of widespread ice and also salt deposits on Mars.

Mars Express

A satellite from the Europea Space Agency that began orbiting Mars on December 25, 2003.

Northern Hemisphere

The _____ is generally much lower than the other Hemisphere, as seen from the topographic map of Mars.

Mars Reconnaissance Orbiter

Numerous steeply sloping narrow linear features were captured on camera by the _______. They turn darker in the Martian summer and disappear when the temperature drops.

Sojourner

Mars Pathfinder’s tiny robot.

NASA’s Curiosity

The largest rover to traipse around Mars, discovered the remains of what was once a freshwater lake.

carbon dioxide

The atmosphere of Mars is mostly _____, but it is much thinner than the atmospheres of Earth or Venus.

South Polar

Dry ice is always present on Mars’s _____ Cap.

Olympus Mons

The largest volcano in the solar system. It is roughly five times wider and nearly three times higher than Mount Loa, the largest volcano on Earth, at 370 miles wide and 15 miles high.

Valles Marineris.

Mars’s large number of canyons, which is 2,490-mile-long.