Space Environment

What is in space?

What is an asteroid, a planetoid, a meteoroid?

Meteors are just bits of dust or rocks from space that get sucked into the Earth's gravitational pull when they come to close to it. As they enter our atmosphere and plummet towards the ground, they burn up, usually about 60 miles before they get close enough to hit you in the head. When the meteors burn up, we on the ground can sometimes see the brief flash of light. This is what people call "shooting stars." Usually, the "space dust" that make meteors comes from the tails of passing comets. Every once in a while, a meteor will be big enough to weather its fiery descent and land on Earth, where it earns the title "meteorite."

Asteroids are also known as "minor planets." They are made up of much of the same stuff as planets, but they are much smaller. The four largest known are spherical or ball-shaped, like the Earth, and have diameters of between 100 and 500 miles. A diameter is an imaginary line running from one side of a circle or sphere through the center to the other side. In comparison to Earth's moon, which has a diameter of about 2100 miles, even the largest asteroids are still pretty small. The rest of the asteroids range in diameter all the way down to less than 5 miles across. Asteroids with diameters of 30 miles or less no longer have a spherical shape. Most asteroids orbit the Sun between Mars and Jupiter. Although some asteroids have sizes comparable to some moons in our solar system, these are not moons because they only orbit the Sun, and not any planets, as the moons do. The largest asteroids are called planetoids.

An asteroid named Gaspra High resolution Gaspra Mosaic, From NASA's Image Exchange Catalog #: PIA00119

What is in space besides planets and stars?
What is a comet?
What is an orbit?
What travels in an orbit?
What is a satellite?
How does gravity work in space?

What are planets made of?
How do asteroids orbit?
What is interstellar dust?

How do we know what's in space?