Solar System

Solar System
Image result for Solar System
This article is about the Sun and its planetary system. For other similar systems, see Planetary system.
Solar System
A representative image of the Solar System with sizes, but not distances, to scale
The Sun and planets
(distances not to scale)
Age4.568 billion years
Location
System mass1.0014 Solar masses
Nearest star
Nearest known planetary systemProxima Centauri system  (4.25 ly)
Planetary system
Semi-major axis of outer known planet (Neptune)30.10 AU  (4.503 billion km)
Distance to Kuiper cliff50 AU
Populations
Stars1  (Sun)
Known planets
Known dwarf planets
Three universally accepted
two named by the IAU under the expectation they will prove to be
Known natural satellites
575
Known minor planets796,354  (as of 2019-08-27)[3]
Known comets4,143  (as of 2019-08-27)[3]
Identified rounded satellites19 (5 or 6 likely to be in hydrostatic equilibrium)
Orbit about Galactic Center
Invariable-to-galactic plane inclination60.19°  (ecliptic)
Distance to Galactic Center27,000 ± 1,000 ly
Orbital speed220 km/s
Orbital period225–250 Myr
Star-related properties
Spectral typeG2V
Frost line≈5 AU[4]
Distance to heliopause≈120 AU
Hill sphere radius≈1–3 ly
Solar System
Solar sys8.jpg
Objects
Lists
Planets
Solar system.jpg Solar System portal
He1523a.jpg Star portal
The Solar System[a] is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.[b] Of the objects that orbit the Sun directly, the largest are the eight planets,[c] with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury.[d]
The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
The Solar System also contains smaller objects.[e] The asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered population of sednoids. Within these populations, some objects are large enough to have rounded under their own gravity, though there is considerable debate as to how many there will prove to be.[9][10] Such objects are categorized as dwarf planets. Identified or accepted dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris.[e] In addition to these two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between regions. Six of the planets, the six largest possible dwarf planets, and many of the smaller bodies are orbited by natural satellites,[f] usually termed "moons" after the Moon. Each of the outer planets is encircled by planetary rings of dust and other small objects.
The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way galaxy.

Comments

Post a Comment

Popular posts from this blog

You may soon be able to ride to the edge of space from Alaska in a Balloon

Image
You may soon be able to ride to the edge of space from Alaska in a Balloon Florida-based startup firm Space Perspective plans to use the Pacific Spaceport Complex in Kodiak to serve as one of the launch sites for the vehicle, called the Spaceship Neptune A company wants to use an advanced balloon to fly customers from Earth’s surface in Alaska to the highest reaches of the planet’s atmosphere. Florida-based startup firm Space Perspective plans to use the Pacific Spaceport Complex in Kodiak to serve as one of the launch sites for the vehicle, called the Spaceship Neptune,  The Anchorage Daily News  reported on Sunday. The balloon rides will be manned by a flight crew taking eight passengers in a pressurized capsule suspended beneath a hydrogen balloon the size of a football stadium. Each passenger could pay an estimated $125,000 for a six-hour journey. Mark Lester, CEO of Alaska Aerospace Corp., said the high-altitude rides will be available from Kodiak in a few years and will ...
Read more

Committee recommends review of planetary protection policies

Image
Committee recommends review of planetary protection policies WASHINGTON — The NASA Advisory Council has recommended that NASA review its existing planetary protection guidelines to balance the needs of science and exploration, an effort that could set the stage for a similar revision at the international level. The council, during a two-day meeting at NASA Headquarters Dec. 10–11, adopted a recommendation calling on NASA to establish an interdisciplinary committee of experts to review the agency’s current requirements for preventing contamination of other worlds by NASA spacecraft as well as any contamination of the Earth by materials brought back from those worlds. “NASA should establish a multidisciplinary task force of experts from industry, the scientific community, and relevant government agencies, to develop U.S. policies that properly balance the legitimate need to protect against the harmful contamination of the Earth or other celestial bodies with the scientific, social, and e...
Read more

Surprise! There's more water on Jupiter than anyone thought

Surprise! There's more water on Jupiter than anyone thought Jupiter  appears to have more water than anyone expected. Newly released data from  NASA's Juno probe shows that water may make up about 0.25% of the molecules in the atmosphere over Jupiter's equator. While that doesn't sound like much, the calculation is based on a prevalence of water's components, hydrogen and oxygen, three times more than at the sun. The new measurements Juno obtained are much higher than a previous mission suggested. The surprise result has scientists delving deep again into results from  NASA's Galileo mission to Jupiter , which obtained drier results in 1995 when engineers deliberately threw the spacecraft into Jupiter's atmosphere. (Galileo was low on fuel and NASA didn't want to take the chance, even if it was a slight one, of the spacecraft accidentally crashing on a potentially habitable icy moon.) Reconciling the results from Galileo and Juno is key for sc...
Read more