The Sun
The time it takes for a planet to orbit the Sun.
What is one year?
The reason we can't breathe on Mercury.
What is there is no atmosphere?
Molten or melted rock that flows from a volcano.
What is lava?
The layer of the Earth just below the Earth's crust and above the core?
What is the mantle?
The largest volcano in the solar system.
What is Olympus Mons?
The number of Earths that would fit inside the Sun.
What is more than one million?
The two NASA spacecraft that have studied Mercury.
What are Messenger and Mariner 10?
The reason that Venus is the hottest planet in the solar system.
What are heavy, thick, heat-trapping clouds?
The equator divides these two halves of the Earth.
What are the Northern Hemisphere and the Southern Hemisphere?
These are Mar's two potato-shaped moons.
What are Phobos and Deimos?
A giant tower of fire that shoots out from the Sun.
What is a solar flare?
The shape of Mercury's orbit.
What is elliptical?
The name given to Venus when it's visible just after the sun sets in the sky.
What is the "evening star"?
A large magnetic field that surrounds the Earth and some other planets.
What is a magnetosphere?
The ice at Mar's poles is composed of these two things.
What are dry ice (CO2) and ice (H2O)?
The temperature of the Sun does this when there are more sunspots.
What is increases?
Astronomers' term for Mercury passing between the Earth and the Sun.
What is "transiting" the Sun?
The tool used to explore the surface of Venus.
What is radar?
The Moon's gravity has this effect on the Earth's oceans.
What are low and high tides?
The rovers on Mars are searching for this.
What is liquid water?
Nuclear reactions that happen on the sun that give it energy and power.
What is thermonuclear fusion?
The best time to see Mercury without a telescope.
What is right before sunrise and right after sunset?
The different shapes Venus appears to take as it orbits the Sun.
What are phases?
This president tasked NASA with sending a man to the moon in the 1960s.
The reason Mar's atmosphere is so thin.
What is the lack of a magnetosphere?