What do you think of when you hear the word “space?” You might think of the Sun and the planets in our solar system. You might picture the billions of stars that light up the sky at night, or asteroids and meteors as they hurtle through the sky. All of these are part of our incredibly vast universe. The solar system including dwarf planet Pluto and the asteroid belt. Gase…
The Earth is unique in the solar system because it is the only planet that we know where life is supported. Animals and plants are abundant. You can see them everywhere! Even the oceans are filled with life. A sea turtle swimming in the ocean. Our planet supports life because of its position in the solar system. At an average distance of about 93 million miles (150 million km), we are the t…
Apart from the Sun, the Earth's Moon is the largest object we can see in the sky. It is the closest object to us in the solar system, yet it is still about 240,000 miles (386,200 km) away! A view of the Moon from Earth. The Moon is covered in craters, which are large bowl-shaped holes in the surface of the Moon caused by collisions with objects such as meteorites. As a satellite…
Until about 500 years ago, most people thought that the Earth was the center of the universe and the Sun and other planets revolved around it. This was called the geocentric model of the universe. We now know that the Sun is at the center of our solar system, a belief that was proposed by the Polish astronomer Nikolai Copernicus in 1543. This is called the heliocentric model, named after the…
A planet is any of the large bodies that orbit the Sun, including Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, in order of closeness to the Sun. Mercury is the first of the four terrestrial planets. This means it is a planet made mostly of rock. The planets closest to the Sun—Venus, Earth, and Mars—are the other three. Mercury is the smallest of the terres…
There are many other objects in our solar system as well as the planets and their moons. There used to be nine planets, and now there are only eight! Did one explode? Did it fly out of the solar system? No, all that happened was that in 2006 scientists decided that Pluto wasn't big enough to be considered a true planet. Pluto has become one of the three known dwarf planets. Pluto A d…
October 4, 1957 Sputnik 1 becomes the first artificial satellite to orbit the Earth. April 12, 1961 Yuri Gagarin becomes the first human in space aboard Vostok 1. May 5, 1961 Alan Shepard, Jr. becomes the first American in space aboard Freedom 7. February 20, 1962 John Glenn becomes the first American to orbit the Earth aboard Friendship 7. June 16, 1963 Valentina Tereshkova b…
asteroids (AS tuh roids) — small bodies that orbit the Sun like planets astronaut (AS troh nawt) — someone who travels in space atmosphere (AT mohs feer) — the layer of gases surrounding the Earth axis (AK sis) — an imaginary line on which a planet or other space object is said to rotate comet (KAH meht) — a ball of ice and dust particles that orbits the Sun dwa…