Astronomical objects known since antiquity

Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is made possible by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation, while large ice sheets at Earth's polar deserts retain more water than Earth

The Sun is the star located at the centre of the Solar System. It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is the main source of energy for life on Earth. The Sun has been an object of veneration in many cultures and a central subject of astronomical research since antiquity.

The Moon is the only natural satellite of Earth. It orbits around Earth at an average distance of , a distance roughly 30 times the width of Earth. It completes an orbit (lunar month) in relation to Earth and the Sun (synodically) every 29.5 days. The Moon and Earth are bound by gravitational attraction, which is stronger on the sides facing each other. The resulting tidal forces are the main driver of Earth's tides, and have pulled the Moon to always face Earth with the same near side. This tidal locking effectively synchronizes the Moon's rotation period (lunar day) to its orbital period (lu

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide (). At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from , and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, fog, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no bodies of liquid surface water. Its surface gravit

Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the mean surface level, the atmosphere reaches a temperature of and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. From Earth, Venus is visible as a star-like point of light, appearing brig

first planet from the Solar System and smallest among all, tellurian and with extreme temperatures

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. It is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at a distance of , with an orbital period of . It is the third-brightest natural object in the Earth's night sky, after the Moon and Venus, and has been observed since prehistoric times. Its name derives from that of Jupiter, the chief deity of ancient Roman religi

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of its mass. Saturn orbits the Sun at a distance of , with an orbital period of 29.45 years.

galaxy containing our Solar System

The Pleiades ( ), also known as Seven Sisters and Messier 45 (M45), is an asterism of an open star cluster containing young B-type stars in the northwest of the constellation Taurus. At a distance of about 444 light-years, it is among the nearest star clusters to Earth and the nearest Messier object to Earth, being the most obvious star cluster to the naked eye in the night sky. It contains the reflection nebulae NGC 1432, an HII region, and NGC 1435, known as the Merope Nebula. Around 2330 BC the Pleiades marked the vernal point. Due to the brightness of its stars, the Pleiades is viewable fr

barred spiral galaxy within the Local Group

Sirius is the brightest star in the night sky, located in the southern constellation of Canis Major. Its name is derived from the Greek word (Latin script: ; ). The star is designated  Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated  CMa or Alpha CMa. With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as Canopus, the next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance betw

short-period comet visible from Earth every 75–76 years

triple star system in the constellation Centaurus, where one of the three stars, Proxima Centauri, being the closest star to the Earth

diffuse nebula

irregular galaxy, satellite of the Milky Way

irregular galaxy, satellite galaxy of the Milky Way

Altair is the brightest star in the equatorial constellation of Aquila and the twelfth-brightest star in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinised from α Aquilae and abbreviated Alpha Aql or α Aql. Altair is an A-type main-sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle asterism; the other two vertices are marked by Deneb and Vega. It is located at a distance of from the Sun. Altair is currently in the G-cloud—a nearby interstellar cloud formed from an accumulation of gas and dust.

Algol , designated Beta Persei (β Persei, abbreviated Beta Per, β Per), known colloquially as the Demon Star, is a bright multiple star in the constellation of Perseus and one of the first non-nova variable stars to be discovered.

Procyon () is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinized to Alpha Canis Minoris, and abbreviated α CMi or Alpha CMi, respectively. As determined by the European Space Agency Hipparcos astrometry satellite, this system lies at a distance of just , and is therefore one of Earth's nearest stellar neighbors. A binary star system, Procyon consists of a white-hued main-sequence star of spectral type F5 IV–V, designated co

globular cluster in the constellation Centaurus

Open cluster

open cluster

Open cluster

Alpheratz is a prominent star system in the constellation of Andromeda. Pronounced , it has the Bayer designation Alpha Andromedae, Latinised from α Andromedae, and abbreviated Alpha And or α And, respectively. Alpheratz is the brightest star in the constellation when Mirach (βAndromedae) undergoes its periodical dimming. Immediately northeast of the constellation of Pegasus, it is the upper left star of the Great Square of Pegasus. It is located at a distance of 97 light-years from Earth.

star in the southern constellation Eridanus

open cluster in the constellation Perseus

open cluster in the constellation Perseus

supernova

star in the constellation Aquarius

open star cluster

non-periodic comet

open cluster in the constellation Coma Berenices

supernova within Scorpius, observed in 393

supernova in the constellation Sagittarius