1.What Is the Planet Mercury?
Mercury is a planet in our solar system. It is the smallest of the eight planets. It is also the closest to the sun. Mercury goes around the sun the fastest of all the planets. Mercury has no moons.
How Did Mercury Get Its Name?
The Romans believed that gods and goddesses were in charge of everything on Earth. Mercury is named after the messenger for their gods. The Roman Mercury had wings on his helmet and shoes. He could travel very quickly from place to place. The planet Mercury moves quickly around the sun. That is how it got its name.
How Big Is Mercury?
Mercury is a little bigger than Earth's moon. It is made of heavier materials, like iron. But if you could weigh Mercury and the moon, Mercury would weigh a lot more. Mercury is heavy, but it is small. It would take more than 18 Mercurys to be as big as Earth.
Where Is Mercury?
Mercury is the closest planet to the sun. Mercury goes around the sun once every 88 Earth days. A day on Mercury lasts a lot longer than a day on Earth. One day on Mercury lasts 59 Earth days.
What Is Mercury Like?
The surface of Mercury looks like Earth's moon. It is covered with holes. The holes are called impact craters. The craters were made by rocks falling from space. The rocks are going very fast when they hit Mercury. A hole is made where the rock hits. Earth has a blanket of air around it. Mercury does not. The blanket is what helps keep Earth from getting too hot or cold. Because it is so close to the sun, Mercury can be very hot. At night, Mercury gets very cold. We could not live on Mercury!
How Has NASA Studied Mercury?
Mercury is hard to study because it is so close to the sun. People have never gone to Mercury. Spacecraft without people have gone. Mariner 10 was the first to visit Mercury. It flew by in 1974 and 1975. Not even half of Mercury was seen then. After that, nothing was sent to Mercury for more than 30 years. NASA's MESSENGER spacecraft flew by Mercury in 2008 and 2009. In March 2011, it began to orbit Mercury. MESSENGER will study parts of Mercury that have not been seen before. It will let scientists learn many new things about the planet.
2.What Is Jupiter?
Jupiter is the largest planet in the solar system. Jupiter is so big that all the other planets in the solar system could fit inside it. More than 1,300 Earths would fit inside Jupiter.
Jupiter is the fifth planet from the sun. From Earth, it is almost always the second brightest planet in the night sky. Venus is brighter. The planet is named after another Jupiter. He was the king of the gods in old Roman stories.
The planet Jupiter is not a solid like Earth is. Jupiter is made of gases. It is made of the same things that stars are made of. In fact, Jupiter would have become a star if it were about 80 times bigger.
What Is Jupiter Like?
The planet is a giant ball of gas. So Jupiter is called a "gas giant" planet. The planet is covered in thick red, brown, yellow and white clouds. The clouds make the planet look like it has stripes. Jupiter is very windy. Its winds blow more than 400 mph. That is faster than hurricanes and tornadoes!
Jupiter is famous for its Great Red Spot. The swirling, red spot is a giant spinning storm. It looks like a hurricane. Almost 3 1/2 Earths would fit across the storm.
Jupiter has three thin rings. Its rings are not like Saturn's rings. Jupiter's rings are hard to see. NASA’s Voyager 1 spacecraft found the rings in 1979. Jupiter’s rings are made up mostly of tiny bits of dust.
Jupiter rotates, or spins, faster than any other planet. Earth takes almost 24 hours to spin once. Jupiter only takes 10. So a day on Jupiter is about 10 hours long. It is so far from the sun that Jupiter takes 12 Earth years to make one trip around the sun. That means one year on Jupiter is 12 years on Earth.
It is very cold on Jupiter. Gravity is different, too. There is more gravity on Jupiter than on Earth. Someone who weighs 100 pounds on Earth would weigh about 240 pounds on Jupiter.
How Many Moons Does Jupiter Have?
Jupiter has 53 named moons. Scientists have discovered 14 more. But those 14 moons do not have official names. Scientists now think Jupiter has a total of 67 moons.
The last time a moon was found was in 2011. The planet’s four largest moons are Ganymede (GAN-i-meed), Callisto (kuh-LIS-toe), Io (eye-OH), and Europa (yur-O-puh). They were found long ago in 1610.
The largest of Jupiter’s moons is named Ganymede. It is the largest moon in the solar system. Ganymede is larger than Mercury and Pluto. The moon Callisto is covered with craters. The moon Io has a lot of volcanoes. Europa is covered with water ice.
How Has NASA Studied Jupiter?
NASA has studied Jupiter from Earth and from space. Some NASA scientists use telescopes on Earth to study Jupiter. The Hubble Space Telescope flies above Earth. It has taken pictures of Jupiter. From 1979 to 2007, eight NASA spacecraft studied Jupiter. Some of those spacecraft