The Solar System and Beyond Supidsara Duangchuai ( 702 ) Ai Thiti hohirunkul ( 702 ) Big
The Sun is the star at the center of the Solar System . It has a diameter of about 1,392,000 kilometers ( 865,000 mi ) , about 109 times that of Earth , and its mass ( about 2 × 10 30 kilograms, 330,000 times that of Earth ) accounts for about 99.86% of the total mass of the Solar System . About three quarters of the Sun's mass consists of hydrogen , while the rest is mostly helium . Less than 2% consists of heavier element including oxygen , carbon , neon , iron , and others . The Sun's color is white, although from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light .] Its stellar classification , based on spectral class, is G2V , and is informally designated a yellow star , because its visible radiation is most intense in the yellow - green portion of the spectrum . The Sun
Mercury is the innermost and smallest planet in the Solar System , [a] orbiting the Sun once every 87.969 Earth days . The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt . It completes three rotations about its axis for every two orbits . The perihelion of Mercury's orbit precesses around the Sun at an excess of 43 arcseconds per century; a phenomenon that was explained in the 20th century by Albert Einstein 's General Theory of Relativity . Mercury is bright when viewed from Earth , ranging from −2.3 to 5.7 in apparent magnitude , but is not easily seen as its greatest angular separation from the Sun is only 28.3° . Since Mercury is normally lost in the glare of the Sun, unless there is a solar eclipse it can be viewed only in morning or evening twilight .
is the second planet from the Sun , orbiting it every 224.7 Earth days. The planet is named after Venus , the Roman goddess of love and beauty. After the Moon , it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth , it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been known as the Morning Star or Evening Star. Venus
Earth (or the Earth ) is the third planet from the Sun , and the densest and fifth-largest of the eight planets in the Solar System . It is also the largest of the Solar System's four terrestrial planets . It is sometimes referred to as the World , the Blue Planet,[note or by its Latin name, Terra .[note Home to millions of species including humans , Earth is currently the only place in the universe where life is known to exist. The planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Earth
Mars Mars is the fourth planet from the Sun in the Solar System . The planet is named after the Roman god of war , Mars . It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance .  Mars is a terrestrial planet with a thin atmosphere , having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth . The rotational period and seasonal cycles of Mars are likewise similar to those of Earth. Mars is the site of Olympus Mons , the highest known mountain within the Solar System, and of Valles Marineris , the largest canyon. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature.  [ 14 ] Unlike Earth, Mars is now geologically and tectonically inactive .[ citation needed ]
Jupiter Jupiter is the fifth planet from the Sun and the largest planet within the Solar System .  It is a gas giant with a mass slightly less than one-thousandth of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn , Uranus and Neptune . Together, these four planets are sometimes referred to as the Jovian planets. The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter .  When viewed from Earth , Jupiter can reach an apparent magnitude of −2.94, making it on average the third-brightest object in the night sky after the Moon and Venus . ( Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System , after Jupiter . Saturn is named after the Roman god Saturn , equated to the Greek Cronus (the Titan father of Zeus ), the Babylonian Ninurta , and the Hindu Shani . Saturn's symbol represents the Roman god's sickle ( Unicode : ♄ ). Saturn, along with Jupiter, Uranus , and Neptune , is classified as a gas giant . Together, these four planets are sometimes referred to as the Jovian, meaning "Jupiter-like", planets. Saturn has an average radius about nine times larger than the Earth's.  While only one-eighth the average density of Earth, due to its larger volume , Saturn's mass is just over ninety-five times greater than Earth's.  saturn
Uranus is the seventh planet from the Sun , and the third-largest and fourth most massive planet in the Solar System . It is named after the ancient Greek deity of the sky Uranus ( Ancient Greek : Οὐρανός ) the father of Cronus ( Saturn ) and grandfather of Zeus ( Jupiter ). Though it is visible to the naked eye like the five classical planets , it was never recognized as a planet by ancient observers because of its dimness and slow orbit.  Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the Solar System for the first time in modern history. Uranus was also the first planet discovered with a telescope . Uranus
Neptune is the eighth and farthest planet from the Sun in our Solar System . Named for the Roman god of the sea , it is the fourth-largest planet by diameter and the third-largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus , which is 15 Earth masses and not as denseOn average, Neptune orbits the Sun at a distance of 30.1 AU , approximately 30 times the Earth-Sun distance. Its astronomical symbol is , a stylized version of the god Neptune's trident . Nepturn
Pluto , formal designation 134340 Pluto , is the second-largest known dwarf planet in the Solar System (after Eris ) and the tenth-largest body observed directly orbiting the Sun . Originally classified as a planet, Pluto is now considered the largest member of a distinct population known as the Kuiper belt . [ note 9] Like other members of the Kuiper belt, Pluto is composed primarily of rock and ice and is relatively small : approximately a fifth the mass of the Earth 's Moon and a third its volume . It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU ( 4.4–7.4 billion km ) from the Sun . This causes Pluto to periodically come closer to the Sun than Neptune .