Planetary Characteristics: Moon, Mercury, Venus, Mars

What feature of the Moon allows it to preserve craters and surface features?

The Moon has no atmosphere.

How can craters on the Moon be classified based on their appearance?

Sharp craters are young, while rounded craters are old; light ejecta indicates new craters.

What is regolith on the Moon?

a dust layer created by micrometeorite impacts.

Why does the far side of the Moon have fewer maria?

thicker crust

What type of rock primarily composes the highlands of the Moon?

anorthosite, which is rich in plagioclase.

What is the origin of the Moon?

a giant impact with Theia approximately 4.5 billion years ago.

What recent geological activity has been observed on the Moon?

There has been no recent volcanic activity on the Moon.

What is unique about Mercury's atmosphere?

no true atmosphere, only a thin exosphere composed of sodium, oxygen, helium, and other elements.

What are the extreme temperature variations on Mercury?

Daytime temperatures reach 800°F, while nighttime temperatures drop to -297°F.

What is the spin-orbit resonance of Mercury?

3:2, with a rotation period of 59 days and a revolution period of 88 days.

What is the Caloris Basin on Mercury?

a major impact crater with weird terrain on the opposite side.

What geological feature on Mercury indicates planetary shrinkage?

Scarps due to cooling.

What is the density of Mercury, and what does it indicate?

5.4 g/cm³, indicating a large iron core.

What missions have explored Mercury?

Mariner 10, MESSENGER, and the upcoming BepiColombo in 2025.

What is the composition of Venus's atmosphere?

96% carbon dioxide and a pressure 92 times that of Earth.

What is the surface temperature of Venus due to its atmosphere?

850°F

What is unique about Venus's rotation?

retrograde rotation, taking 243 days for a day and 225 days for a year.

What geological features are found on Venus?

pancake domes, a basaltic surface, and few craters due to its dense atmosphere.

How long ago did Venus resurface?

approximately 500 million years ago.

What missions have studied Venus?

Magellan, Venera, DAVINCI, and VERITAS.

What is the atmosphere of Mars like?

a thin atmosphere composed mainly of carbon dioxide, at about 1% of Earth's atmosphere.

What are the day and year lengths on Mars?

about 24.6 hours, and a year is 687 days.

What is Olympus Mons?

the tallest volcano in the solar system, located on Mars.

What is Valles Marineris?

deepest canyon in the solar system, found on Mars.

What evidence of water has been found on Mars?

jarosite, hematite 'blueberries', and cross-bedding.

What happened to Mars' magnetic field?

lost its magnetic field, which led to the loss of its atmosphere and the inability to retain liquid water.

What atmospheric phenomena are common on Mars?

dust storms and has polar carbon dioxide caps.

What missions have explored Mars?

Viking, Pathfinder, Curiosity, and Perseverance.

What are the main differences between Venus and Earth regarding CO₂ regulation?

Venus has a runaway greenhouse effect with no CO₂ regulation, while Earth's CO₂ is regulated by water and life, leading to limestone formation.

How does the lack of a magnetic field affect Venus?

its atmosphere is unprotected.

What is notable about Venus's rotation compared to Earth?

Venus has a retrograde rotation, which is opposite to most planets, including Earth.