Solar System Exploration: Solar System 101: Homework Helper

HOMEWORK HELPER

The Swiftest Planet
Sun-scorched Mercury is only slightly larger than Earth's Moon. Like the Moon, Mercury has very little atmosphere to stop impacts, and it is covered with craters. Mercury's dayside is super-heated by the sun, but at night temperatures drop hundreds of degrees below freezing. Ice may even exist in craters. Mercury's egg-shaped orbit takes it around the sun every 88 days.

Extreme Facts

Catastrophic Crash The impact that created Mercury's Texas-sized Caloris Basin equaled roughly 1,000,000,000,000 1-megaton hydrogen bombs. The shockwave from the collision was so powerful it created a hilly region the size of Germany and France on the opposite side of the planet.

Double Sunrise Because of Mercury's elliptical -- egg-shaped -- orbit and sluggish rotation, the morning sun appears to rise briefly, set and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset.

Made in the Shade Even though it will be working in temperatures up to 840 degrees Fahrenheit (about 450 degrees Celsius), sensitive parts of the MESSENGER spacecraft will remain at a pleasant room temperature thanks to a heat-resistant ceramic cloth sunshade.

Running Hot and Cold Mercury is not only one of the hottest places in our solar system -- it's also among the coldest. As darkness falls on Mercury, temperatures can drop more than 1,080 degrees Fahrenheit (600 degrees Celsius).

Speed Racer True to its namesake (the speedy messenger of ancient Roman gods), Mercury is the fastest planet in our solar system. It zips around our sun at an average of 172 thousand kph (107 thousand mph) -- about 65 thousand kph (40 thousand mph) faster than Earth. A year on Mercury is equal to 88 Earth days.

The Long and the Short of It Mercury completes three rotations for every two orbits around the sun. That means if you wanted to stay up from sunrise to sunrise on Mercury, you'd be up for 176 Earth days.

Artsy Planet Craters and features on Mercury are named after famous deceased artists, musicians or authors, including children's author Dr. Seuss and dance pioneer Alvin Ailey.

Moonless Night Mercury does not have a moon to brighten it's night skies. Mercury is one of only two planets in our solar system that do not have moons. (Venus is the other one.)

Solar Power MESSENGER, the first and only spacecraft to orbit the planet Mercury, gathers most of its power from the sun through its solar array. However, since Mercury is extremely close to the sun, the solar arrays are also designed to rotate away from the sun to avoid overheating.

Elusive Planet When Mariner 10 flew by Mercury (1974 and 1975) the spacecraft was only able to image 45% of the surface. This was due to the spacecraft's period of orbit: Each time the spacecraft flew by the innermost planet the sun happened to be illuminating the same side of Mercury. Scientists and the general public had to wait nearly 35 years between the Mariner 10 and the MESSENGER missions to see for the first time a map of the surface of the planet Mercury.

Waterhole There isn't much on the surface of Mercury other than impact features, such as craters and pits. But within some of those craters and pits there could be water. Evidence has been found to suggest that there is water ice within the permanently shadowed, polar regions on Mercury.

Don't Forget Your Sunglasses The MESSENGER spacecraft has its own shades to protect it from the light of the sun. This is important since sunlight on Mercury can be as much as 11 times brighter than it is here on Earth. And this sunlight, with harsher heat conditions, can severely damage a spacecraft. So instead of the sleek reflective gear we wear to protect our eyes, the MESSENGER spacecraft must wear a sunshade made out of heat-resistance ceramic cloth.

Catastrophic Crash The impact that created Mercury's Texas-sized Caloris Basin equaled roughly 1,000,000,000,000 1-megaton hydrogen bombs. The shockwave from the collision was so powerful it created a hilly region the size of Germany and France on the opposite side of the planet.

Double Sunrise Because of Mercury's elliptical -- egg-shaped -- orbit and sluggish rotation, the morning sun appears to rise briefly, set and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset.

Made in the Shade Even though it will be working in temperatures up to 840 degrees Fahrenheit (about 450 degrees Celsius), sensitive parts of the MESSENGER spacecraft will remain at a pleasant room temperature thanks to a heat-resistant ceramic cloth sunshade.

Running Hot and Cold Mercury is not only one of the hottest places in our solar system -- it's also among the coldest. As darkness falls on Mercury, temperatures can drop more than 1,080 degrees Fahrenheit (600 degrees Celsius).

Speed Racer True to its namesake (the speedy messenger of ancient Roman gods), Mercury is the fastest planet in our solar system. It zips around our sun at an average of 172 thousand kph (107 thousand mph) -- about 65 thousand kph (40 thousand mph) faster than Earth. A year on Mercury is equal to 88 Earth days.

The Long and the Short of It Mercury completes three rotations for every two orbits around the sun. That means if you wanted to stay up from sunrise to sunrise on Mercury, you'd be up for 176 Earth days.

Artsy Planet Craters and features on Mercury are named after famous deceased artists, musicians or authors, including children's author Dr. Seuss and dance pioneer Alvin Ailey.

Moonless Night Mercury does not have a moon to brighten it's night skies. Mercury is one of only two planets in our solar system that do not have moons. (Venus is the other one.)

Solar Power MESSENGER, the first and only spacecraft to orbit the planet Mercury, gathers most of its power from the sun through its solar array. However, since Mercury is extremely close to the sun, the solar arrays are also designed to rotate away from the sun to avoid overheating.

Elusive Planet When Mariner 10 flew by Mercury (1974 and 1975) the spacecraft was only able to image 45% of the surface. This was due to the spacecraft's period of orbit: Each time the spacecraft flew by the innermost planet the sun happened to be illuminating the same side of Mercury. Scientists and the general public had to wait nearly 35 years between the Mariner 10 and the MESSENGER missions to see for the first time a map of the surface of the planet Mercury.

Waterhole There isn't much on the surface of Mercury other than impact features, such as craters and pits. But within some of those craters and pits there could be water. Evidence has been found to suggest that there is water ice within the permanently shadowed, polar regions on Mercury.

Don't Forget Your Sunglasses The MESSENGER spacecraft has its own shades to protect it from the light of the sun. This is important since sunlight on Mercury can be as much as 11 times brighter than it is here on Earth. And this sunlight, with harsher heat conditions, can severely damage a spacecraft. So instead of the sleek reflective gear we wear to protect our eyes, the MESSENGER spacecraft must wear a sunshade made out of heat-resistance ceramic cloth.