Age
|
4.568 billion
years
|
Location
|
|
System mass
|
1.0014 Solar masses
|
Nearest star
|
·
Proxima Centauri (4.25 ly)
·
Alpha Centauri (4.37 ly)
|
Nearest known planetary system
|
Proxima Centauri system (4.25 ly)
|
Planetary system
|
|
Semi-major axis of outer known planet (Neptune)
|
30.10 AU
(4.5 bill. km; 2.8 bill. mi) |
Distance to Kuiper cliff
|
50 AU
|
Populations
|
|
Stars
|
1 (Sun)
|
Known planets
|
|
Known dwarf planets
|
3 universally accepted
2 more expected to be
|
Known natural satellites
|
|
Known minor planets
|
796,354
|
Known comets
|
4,143
|
Identified rounded satellites
|
19 (5–6 likely in hydrostatic
equilibrium)
|
Orbit about Galactic Center
|
|
Invariable-to-galactic plane inclination
|
60.19° (ecliptic)
|
Distance to Galactic Center
|
27,000 ± 1,000 ly
|
Orbital speed
|
220 km/s; 136 mps
|
Orbital period
|
225–250 myr
|
Star-related
properties
|
|
≈5 AU
|
|
Distance to heliopause
|
≈120 AU
|
Hill sphere radius
|
≈1–3 ly
|
Comprehensive overview of the Solar System. The Sun, planets, dwarf planets and moons are at scale for their relative sizes, not for distances. A separate distance scale is at the bottom. Moons are listed near their planets by proximity of their orbits; only the largest moons are shown
Inner Solar System
The inner Solar System is the region comprising the terrestrial planets and the asteroid belt. Composed mainly of silicates and metals, the objects of the inner Solar System are relatively close to the Sun; the radius of this entire region is less than the distance between the orbits of Jupiter and Saturn. This region is also within the frost line, which is a little less than 5 AU (about 700 million km) from the Sun.Inner planets
The four terrestrial or inner planets have dense, rocky compositions, few or no moons, and no ring systems. They are composed largely of refractory minerals, such as the silicates—which form their crusts and mantles—and metals, such as iron and nickel, which form their cores. Three of the four inner planets (Venus, Earth and Mars) have atmospheres substantial enough to generate weather; all have impact craters and tectonic surface features, such as rift valleys and volcanoes. The term inner planet should not be confused with inferior planet, which designates those planets that are closer to the Sun than Earth is (i.e. Mercury and Venus).
Mercury
Mercury (0.4 AU from the Sun) is the closest planet to the Sun and on average, all seven other planets. The smallest planet in the Solar System (0.055 M⊕), Mercury has no natural satellites. Besides impact craters, its only known geological features are lobed ridges or rupes that were probably produced by a period of contraction early in its history. Mercury's very tenuous atmosphere consists of atoms blasted off its surface by the solar wind. Its relatively large iron core and thin mantle have not yet been adequately explained. Hypotheses include that its outer layers were stripped off by a giant impact, or that it was prevented from fully accreting by the young Sun's energy.Venus
Venus (0.7 AU from the Sun) is close in size to Earth (0.815 M⊕) and, like Earth, has a thick silicate mantle around an iron core, a substantial atmosphere, and evidence of internal geological activity. It is much drier than Earth, and its atmosphere is ninety times as dense. Venus has no natural satellites. It is the hottest planet, with surface temperatures over 400 °C (752 °F), most likely due to the amount of greenhouse gases in the atmosphere. No definitive evidence of current geological activity has been detected on Venus, but it has no magnetic field that would prevent depletion of its substantial atmosphere, which suggests that its atmosphere is being replenished by volcanic eruptions.Earth
Earth (1 AU from the Sun) is the largest and densest of the inner planets, the only one known to have current geological activity, and the only place where life is known to exist. Its liquid hydrosphere is unique among the terrestrial planets, and it is the only planet where plate tectonics has been observed. Earth's atmosphere is radically different from those of the other planets, having been altered by the presence of life to contain 21% free oxygen. It has one natural satellite, the Moon, the only large satellite of a terrestrial planet in the Solar System.Mars
Mars (1.5 AU from the Sun) is smaller than Earth and Venus (0.107 M⊕). It has an atmosphere of mostly carbon dioxide with a surface pressure of 6.1 millibars (roughly 0.6% of that of Earth).Its surface, peppered with vast volcanoes, such as Olympus Mons, and rift valleys, such as Valles Marineris, shows geological activity that may have persisted until as recently as 2 million years ago. Its red colour comes from iron oxide (rust) in its soil. Mars has two tiny natural satellites (Deimos and Phobos) thought to be either captured asteroids, or ejected debris from a massive impact early in Mars's historyOuter Solar System
The outer region of the Solar System is home to the giant planets and their large moons. The centaurs and many short-period comets also orbit in this region. Due to their greater distance from the Sun, the solid objects in the outer Solar System contain a higher proportion of volatiles, such as water, ammonia, and methane than those of the inner Solar System because the lower temperatures allow these compounds to remain solid.Outer planets
The four outer planets, or giant planets (sometimes called Jovian planets), collectively make up 99% of the mass known to orbit the Sun. Jupiter and Saturn are together more than 400 times the mass of Earth and consist overwhelmingly of hydrogen and helium. Uranus and Neptune are far less massive—less than 20 Earth masses (M⊕) each—and are composed primarily of ices. For these reasons, some astronomers suggest they belong in their own category, ice giants. All four giant planets have rings, although only Saturn's ring system is easily observed from Earth. The term superior planet designates planets outside Earth's orbit and thus includes both the outer planets and Mars.Jupiter
Jupiter (5.2 AU), at 318 M⊕, is 2.5 times the mass of all the other planets put together. It is composed largely of hydrogen and helium. Jupiter's strong internal heat creates semi-permanent features in its atmosphere, such as cloud bands and the Great Red Spot. Jupiter has 79 known satellites. The four largest, Ganymede, Callisto, Io, and Europa, show similarities to the terrestrial planets, such as volcanism and internal heating. Ganymede, the largest satellite in the Solar System, is larger than Mercury.Saturn
Saturn (9.5 AU), distinguished by its extensive ring system, has several similarities to Jupiter, such as its atmospheric composition and magnetosphere. Although Saturn has 60% of Jupiter's volume, it is less than a third as massive, at 95 M⊕. Saturn is the only planet of the Solar System that is less dense than water. The rings of Saturn are made up of small ice and rock particles. Saturn has 82 confirmed satellites composed largely of ice. Two of these, Titan and Enceladus, show signs of geological activity. Titan, the second-largest moon in the Solar System, is larger than Mercury and the only satellite in the Solar System with a substantial atmosphere.Uranus
Uranus (19.2 AU), at 14 M⊕, is the lightest of the outer planets. Uniquely among the planets, it orbits the Sun on its side; its axial tilt is over ninety degrees to the ecliptic. It has a much colder core than the other giant planets and radiates very little heat into space. Uranus has 27 known satellites, the largest ones being Titania, Oberon, Umbriel, Ariel, and Miranda.Neptune
Neptune (30.1 AU), though slightly smaller than Uranus, is more massive (17 M⊕) and hence more dense. It radiates more internal heat, but not as much as Jupiter or Saturn.[103] Neptune has 14 known satellites. The largest, Triton, is geologically active, with geysers of liquid nitrogen.[104] Triton is the only large satellite with a retrograde orbit. Neptune is accompanied in its orbit by several minor planets, termed Neptune trojans, that are in 1:1 resonance with it.Unit Conversions III
1 Astronomical Unit = 1.0 AU = 1.49 x 108 kilometers
1 Parsec = 3.26 Light years = 3 x 1018 centimeters = 206,265AU
1 Watt = 107 ergs/sec 1 Star = 2 x 10 33 grams
1 Yard = 36 inches
1 meter = 39.37 inches
1 mile = 5,280 feet 1 Liter = 1000 cm3
1 inch = 2.54 centimeters 1 kilogram = 2.2 pounds
1 Gallon = 3.78 Liters 1 kilometer = 0.62 miles
1) Length of a year. 31,560,000.0 seconds Answer: 3.156 x 107 seconds
2) Speed of light: 299,792.4 kilometers/sec
Answer: 2.997924 x 105 km/sec
3) Mass of the sun: 1,989,000,000,000,000,000,000,000,000,000,000 grams Answer: 1.989 x 10 power33 grams
4) Mass of Earth: 5,974,000,000,000,000,000,000,000 kilograms Answer: 5.974 x 10 power 24 kg
5) One light-year : 9,460,500,000,000 kilometers Answer: 9.4605 x 10 power12 km
6) Power output of sun : 382,700,000,000,000,000,000,000,000 watts Answer: 3.827 x 10 power 26 watts
7) Mass of an electron: 0.00000000000000000000000000000091096 kilograms Answer: 9.10power 96 x 10-31 kg
8) Energy equivalent of one electron-Volt : 0.00000000000000000016022 joules Answer: 1.6022 x 10power -19 Joules
9) Ratio of proton to electron mass: 1,836.2 Answer; 1.8362 x 10power3
10) Planck's Constant: 0.000000000000000000000000006626068 ergs seconds Answer: 6.626068 x 10power-27 ergs seconds
11) Radius of hydrogen atom : 0.00000000529177 centimeters Answer: 5.29177 x 10power-9 cm
12) Radius of Earth's orbit: 14,959,789,200,000 centimeters Answer: 1.49597892 x 10 power13 cm
13) Smallest unit of physical distance: 0.0000000000000000000000000000000016 centimeters Answer: 1.6 x 10power -33 cm
14) Diameter of Visible Universe: 26,000,000,000,000,000,000,000,000,000 centimeters Answer; 2.6 x 10 power28 cm
