–      Astronomy is the study of the outer space outside of our planet.

–      It includes objects such as planets, moons, stars, comets and meteors, and uses instruments such as telescopes, satellites and space shuttles.

–      When you look up into the night sky, you can see various bright objects, most of which are stars. However, some of these objects are planets and man-made satellites.


–      You may find it difficult to observe stars in cities due to the amount of “light pollution” (man-made lights at night) in your area.  If you were able to travel north of the city and look into the sky on a clear night, you would see countless numbers of stars.

–      Many stars exist in groups together called constellations.  People who existed thousands of years ago identified these constellations and assigned names to them.

–      The most well known star constellation is a seven-star group called “Ursa Major”.  Ursa Major is also called the “Big Dipper.”

–      Some constellations no longer look the same as they did thousands of years ago since stars move over time.

–      Star constellations have been used throughout history to help people determine which direction they are traveling.


–      Our solar system is just one small portion of an incredibly large universe.

–      Our solar system has both luminous and nonluminous objects. A luminous object is one that can provide its own light from nuclear reactions (ex. Stars).  A nonluminous object does not provide light; it only appears to be lit up when a luminous object shines upon it (ex. Planets and Moons).

–      When looking at the night sky, there are five planets we can see throughout the year without using binoculars or telescopes.  They are: Mercury, Venus, Mars (appears slightly orange instead of white), Jupiter and Saturn.  These planets routinely appear larger than the stars in the sky because they are much closer to our planet.  In order to see Uranus, Neptune, and Pluto, a telescope must be used.


Feature Planet Star
Look Located orbiting around stars. One is in our solar system (the Sun) and the rest are very far away from our planet.
Size Smaller than stars. Most are larger than planets.
Light Production Does not produce light; is only visible because they reflect light from nearby stars. Produce their own light through nuclear reactions usually between H and He.
SurfaceTemperature Unless they are right next to a star (such as Mercury), most are cool or very cold. Extremely hot.
Composition(What the object is made of) There are two types of planets: those made out of rocks (ex. Earth) and those made out of gases (ex. Jupiter). Made out of gases that are under very high pressure and temperature.
ObservableFeature Light from them is steady (they do not appear to “twinkle”). Light appears to “twinkle.”
Long-termObservable features Wanders very slowly through different star constellations. Moves as a gas within a star constellation.
author avatar
William Anderson (Schoolworkhelper Editorial Team)
William completed his Bachelor of Science and Master of Arts in 2013. He current serves as a lecturer, tutor and freelance writer. In his spare time, he enjoys reading, walking his dog and parasailing. Article last reviewed: 2022 | St. Rosemary Institution © 2010-2024 | Creative Commons 4.0

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