Astronomy Terms

What is a star?

A celestial body that is made up of hot gases, mainly hydrogen and some helium.

What is a planet?

An object that orbits one or more stars (and isn’t a star itself,) is spherical, and doesn’t share its orbit with another object.

What is a galaxy?

A collection of stars, gas, dust, and planets held together by gravity.

What is the universe?

Everything that exists everywhere, including space, time, matter, and energy.

What is dark matter?

The most abundant form of matter in the universe.

What is a solar eclipse?

The phenomenon in which the Moon’s shadow falls onto Earth’s surface.

What is a lunar eclipse?

The phenomenon in which the Moon enters Earth’s shadow.

What is the aurora?

A natural light display in the sky above the poles, caused by charged particles from the sun colliding with Earth’s atmosphere.

What is Astronomical Unit?

The average distance between the Sun and Earth, about 150 000 000km.

What is a light year?

The distance that light travels in one year, about 9.5 × 10 (to the power of 12) km.

What is a solstice?

The time of year when the sun reaches its highest and lowest point in the sky at noon, resulting in the longest or shortest day of the year.

What is an equinox?

The time of year when the day and night are nearly equal because the sun is right above the Earth’s equator.