What is astronomy? It is the study of our universe, including celestial objects (stars, planets, galaxies, and so on), space phenomena (supernova radiation, gamma ray bursts, cosmic radiation, and more), and the science of how it works (physics, chemistry, etc). It's a natural science.

The solar system our planet is in is in a galaxy named the Milky Way. In it, there are 8 planets that orbit the sun, which is in the center of the solar system. All planets have a counter-clockwise orbit. The 8 planets' names are, in order from closest to farthest from the sun, Mercury, Venus, Earth (where we live), Mars, Jupiter, Saturn, Neptune, and Uranus.

The planets are separated into two parts: the inner solar system and the outer solar system. The inner solar system is made up of Mercury, Venus, Earth, and Mars. The outer solar system is made up of Jupiter, Saturn, Neptune, and Uranus. The two parts of the solar system are separated by an asteroid belt between Mars and Jupiter.

What is a star? "A star is a ball of hydrogen and helium that has enough mass to maintain nuclear fission at its core." The luminosity of the star is caused by its nuclear fission.

Historically, stars have roles in religion and navigation. The stars in the sky can form shapes, which are called constellations. The International Astronomical Union in 1929 recognized 88 constellations, which are the only 'official' ones. Asterisms are constellations within larger ones, such as the Big Dipper, which is inside of Ursa Major.

The recognized constellations are: Andromeda ("The Chained Lady"), Antlia ("The Airpump"), Apus ("The Bird of Paradise"), Aquarius ("The Water Bearer"), Aquila ("The Eagle"), Ara ("The Altar"), Aries ("The Ram"), Auriga ("The Charioeert"), Boötes ("The Herdsman"), Caelum ("The Sculptor's Tool"), Camelopardalis ("The Giraffe"), Cancer ("The Crab"), Canes Venatici ("The Hunting Dogs"), Canis Major ("The Great Dog"), Canis Minor ("The Little Dog"), Capricornus ("The Goat), Carina ("The Keel of the Argo"), Cassiopeia ("The Seated Queen"), Centaurus ("The Centaur"), Cepheus ("The King"), Cetus ("The Whale"), Chameleon, Circinus ("The Compasses"), Columba ("The Dove"), Coma Berenices ("Bernice's Hair"), Corona Australis ("The Southern Crown"), Corona Borealis ("The Northern Crown"), Corvus ("The Crow/Raven"), Crater ("The Cup"), Crux ("The Southern Cross"), Cygnus ("The Swan"), Delphinus ("The Dolphin"), Dorado ("The Swordfish/Goldfish"), Draco ("The Dragon"), Equuleus ("The Filly"), Eridanus ("The Eridanus River"), Fornax ("The Furnace"), Gemini ("The Twins"), Grus ("The Crane"), Hercules ("The Hero"), Horologium ("The Clock"), Hydra ("The Sea Serpent"), Hydrus ("The Water Snake"), Indus ("The Indian"), Lacerta ("The Lizard"), Leo ("The Lion"), Leo Minor ("The Little Lion"), Lepus ("The Hare"), Libra ("The Scales"), Lupus ("The Wolf"), Lynx ("The Lynx"), Lyra ("The Harp"), Mensa (“The Table” or “The Mountain”), Microscopium (“The Microscope”), Monoceros (“The Unicorn”), Musca (“The Southern Fly”), Norma (“The Rule”), Octans (“The Octant”), Ophiuchus (“The Serpent-Bearer”), Orion (“The Hunter”), Pavo (“The Peacock”), Pegasus, Perseus, Phoenix, Pictor (“The Painter/Painter’s Easel”), Pisces (“The Fish”), Piscis Austrinus (“The Southern Fish”), Puppis (“The Poop Deck of the Argo”), Pyxis (“The Mariner’s Compass”), Reticulum (“The Net”), Sagitta (“The Arrow”), Sagittarius (“The Archer”), Scorpius (“The Scorpion”), Sculptor (“The Sculptor”), Scutum (“The Shield”), Serpens (“The Serpent”), Sextans (“The Sextant”), Taurus (“The Bull”), Telescopium (“The Telescope”), Triangulum (“The Triangle”), Triangulum Australe (“The Southern Triangle”), Tucana (“The Toucan”), Ursa Major (“The Great Bear”), Ursa Minor (“The Little Bear”, Vela (“The Sail of the Argo”), Virgo (“The Virgin”), Volans (“The Flying Fish”), and Vulpecula (“The Fox”)

The bolded ones are the 12 that are more or less on the Equator and are used as the signs of the Zodiac.