This planet has an atmospheric composition of 78% nitrogen, 21% oxygen, 0.93% argon, and 0.038% carbon dioxide. It is the only planet that has liquid water.
What is the Earth?
100
The shape of the illuminated portion of the Moon as seen on Earth. These change cyclically as the Moon orbits the Earth.
What is are lunar phases/phases of the moon?
100
The distance which a ray of light would travel in one year. This is about 6,000,000,000,000 (6 trillion) miles.
What is a light year?
100
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
What is a galaxy?
100
A large explosion that takes place at the end of a star's life cycle.
What is a supernova?
200
This planet has the shortest orbit and is the smallest of all the planet in the solar system. A year on this planet is only 88 Earth days.
What is Mercury?
200
When a full moon appears particularly large in the sky because of its perigee, the point of orbit closest to the Earth.
What is a supermoon?
200
The speed an object must have in order to escape from another object's gravity.
What is escape velocity?
200
A spiral galaxy approximately 2.5 million light-years from earth. It is the nearest major galaxy to the Milky Way. Astronomers predict that this galaxy will collide with the Milky Way galaxy in about 4 billion years.
What is the Andromeda Galaxy?
200
At the center of a black hole is this one-dimensional point which contains a huge mass in an infinitely small space.
What is a singularity?
300
This planet is the second largest terrestrial planet and has a retrograde rotation, meaning it rotates in the opposite direction of the sun. It is named after the Roman goddess of love.
What is Venus?
300
When the Earth lines up directly between the sun and the moon, it blocks the light from the sun to the moon. Earth's shadow then falls on the moon, making the moon appear red or orange. This happens at least twice every year.
What is a lunar eclipse?
300
A unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun.
What is an astronomical unit?
300
This is found at the center of almost all known massive galaxies. The one found at the center of the Milky Way Galaxy is called Sagittarius A*.
What is a supermassive black hole?
300
One of this unit of measurement is equivalent to 3.26 light years. It is the distance at which one astronomical unit subtends an angle of one arc second. This term is a combination of 2 words, parallax and arc second.
What is a parsec?
400
The atmosphere of this planet is made up of 80% hydrogen, 19% helium, and 1.5% methane. Methane absorbs red light, making this planet appear blue.
What is Neptune?
400
The moon is in this type of rotation with the Earth meaning the same side is always facing the Earth.
What is a synchronous rotation?
400
Weak microwave radiation coming from space in all directions. It is believed to be the remnant of the Big Bang.
What is background radiation?
400
Galaxies are identified as one of three types: Elliptical, Irregular, and this. The Milky Way and Andromeda are this type of galaxy.
What is a spiral?
400
A system of two stars that rotate around a common center of mass. Polaris (the pole star of the Northern Hemisphere of Earth) is part of this system.
What is a binary star?
500
Often referred to as an "ice giant", this planet is nearly the coldest planet in the solar system. One orbit around the sun takes 84 Earth years for this planet.
What is Uranus?
500
The point of the moon's orbit farthest from the Earth.
What is lunar apogee?
500
The point directly above your head in the night sky.
What is zenith?
500
The Milky Way galaxy falls within this group, which is a poor and irregular cluster of galaxies. Poor clusters may contain only a few dozen galaxies, as compared to rich clusters with hundreds or even thousands.
What is the Local Group?
500
A phonograph record that was included on Voyager 1 and 2. It is a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth.