Space Basics
This specific altitude of 100 km above sea level is considered the official start of outer space.
What is the Karman Line?
Often called "big dirty snowballs," these are made of frozen gases, rock, and dust.
What are comets?
This is the primary difference between a star and a moon/planet regarding light.
What is being luminous (stars) vs. non-luminous (moons/planets)?
Stars are giant balls of hot gas made mostly of these two elements.
What are hydrogen and helium?
This is the speed range, in kilometers per second, at which meteoroids typically travel.
What is 10 to 70 km/s?
While Earth has billions of particles per cubic centimeter, space is a "near-perfect" version of this, containing only about 1 atom per cm³.
What is a vacuum?
A comet has two tails: a yellow one made of dust and a blue one made of these.
What are ions?
These four planets make up the "Gas Giants" of our solar system.
What are Jupiter, Saturn, Uranus, and Neptune?
Our home galaxy, the Milky Way, is estimated to contain this many stars.
What is 100 to 400 billion?
The Milky Way galaxy is approximately this many light-years wide.
What is 100,000 light-years?
This term describes the "scattered matter" found in space, including hydrogen atoms, cosmic dust, and cosmic rays.
What is the interstellar medium?
This is the name for a piece of rock or dust that survives its trip through the atmosphere and actually hits the ground.
What is a meteorite?
To be defined as a planet by the IAU, an object must orbit the sun, be round, and perform this action regarding debris.
What is clearing its orbit?
Scientists classify galaxies into these three basic shapes.
What are spiral, elliptical, and irregular?
A famous crater in Arizona is 1,200 meters wide; it was created by a meteorite that was only about this wide.
What is 40 meters?
This famous telescope launched on Christmas Day in 2021 and provided its first images in July 2022.
What is the James Webb Space Telescope?
Most of these rocky objects are found in a "belt" located between the orbits of Mars and Jupiter.
What are asteroids?
These are the four "Rocky" or Terrestrial planets.
What are Mercury, Venus, Earth, and Mars?
This is the name of our neighboring galaxy, which is roughly 220,000 light-years wide.
What is the Andromeda galaxy?
The longest recorded comet tail was 580 million km, which is about this many times the distance between Earth and the Sun.
What is four times?
These two mysterious components are listed as part of the environment of space alongside magnetic fields and radiation.
What are Dark Matter and Dark Energy?
While most asteroids are made of silicate (stone), some are composed of these two metals.
What are iron and nickel?
A moon is defined as an object that orbits a planet or another body that is specifically NOT one of these.
What is a star?
Astronomers estimate the entire universe could contain up to this many stars (a one followed by 24 zeros).
What is one septillion?
Asteroids can range in size from as small as a pebble to as large as this many kilometers across.
What is 1,000 kilometers?