This fiery swath was actually only a belt of minor planets, almost like the asteroid belt in the original Solar System.

Asteroids ( from Greek ἀστεροειδής-asteroeidēs, " star-like ", from " star " and " like, in form ") are a class of small Solar System bodies in orbit around the Sun.

These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as small objects in the outer Solar System were discovered, their volatile-based surfaces were found to more closely resemble comets, and so were often distinguished from traditional asteroids.

Thus the term asteroid has come increasingly to refer specifically to the small bodies of the inner Solar System out to the orbit of Jupiter, which are usually rocky or metallic.

This article will restrict the use of the term ' asteroid ' to the minor planets of the inner Solar System.

The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our galaxy, the Milky Way.

An equivalent definition is the radius of an unperturbed circular Newtonian orbit about the Sun of a particle having infinitesimal mass, moving with an angular frequency of radians per day ; or that length such that, when used to describe the positions of the objects in the Solar System, the heliocentric gravitational constant ( the product GM < sub >☉</ sub >) is equal to ()< sup > 2 </ sup > AU < sup > 3 </ sup >/ d < sup > 2 </ sup >.

" As such, the meter is undefined for the purposes of measuring distances within the Solar System.

High-energy cosmic rays impacting Earth's atmosphere ( or any other matter in the Solar System ) produce minute quantities of antiparticles in the resulting particle jets, which are immediately annihilated by contact with nearby matter.

* 1989 – Voyager 2 spacecraft makes its closest approach to Neptune, the second to last planet in the Solar System at the time.

Note: because Solar System bodies are never perfect diffuse reflectors, astronomers use empirically derived relationships to predict apparent magnitudes when accuracy is required.

This interdisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in outer space.

Druyan was responsible for the selection of the music on the Voyager Golden Record for the pioneering exploratory missions of the Solar System — Voyager 1 and Voyager 2.

Also, general relativity has passed stringent tests on the scale of the Solar System and binary stars while extrapolation to cosmological scales has been validated by the empirical successes of various aspects of the Big Bang theory.

The remaining 14 naturally occurring elements possess half lives too short for them to have been present at the beginning of the Solar System, and are therefore considered to be transient elements.

Some of these elements, notably thorium ( atomic number 90 ) and uranium ( atomic number 92 ), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy elements before the formation of our Solar System.

The abundance of elements in the Solar System is in keeping with their origin from nucleosynthesis in the Big Bang and a number of progenitor supernova stars.

* Comets Page at NASA's Solar System Exploration

* Catalogue of the Solar System Small Bodies Orbital Evolution

* The Study of Climate on Alien Worlds ; Characterizing atmospheres beyond our Solar System is now within our reach Kevin Heng July-August 2012 American Scientist

* Colonization of Ceres, has been proposed as one possible target for human colonization in the inner Solar System

In most common usage, the term is used for the approximately circular depression in the surface of a planet, moon or other solid body in the Solar System, formed by the hypervelocity impact of a smaller body with the surface.

The cratering records of very old surfaces, such as Mercury, the Moon, and the southern highlands of Mars, record a period of intense early bombardment in the inner Solar System around 3. 9 billion years ago.

Mars has the largest volcano in the Solar System called Olympus Mons, which is more than three times the height of Mount Everest, with a diameter of 520 km ( 323 miles ).

Unbound free-floating planetary-mass bodies in the Milky Way may number in the trillions, with 100, 000 objects larger than Pluto for every main-sequence star .< ref > Nomads of the Galaxy, Louis E. Strigari, Matteo Barnabe, Philip J. Marshall, Roger D. Blandford ; estimates 700 objects > 10 < sup >- 6 </ sup > Solar masses (≈ a Mars mass ) per main sequence star between 0. 08 and 1 Solar mass, of which there are billions in the Milky Way .</ ref >

The costs and risk of interplanetary travel receive a lot of publicity — spectacular examples include the malfunctions or complete failures of unmanned probes such as Mars 96, Deep Space 2 and Beagle 2 ( the article List of Solar System probes gives a full list ).

* Mars 2001 Odyssey Mission Profile by NASA's Solar System Exploration

Mars was one of the three Homeworlds and the industrial center of the Solar System before the war between Terrans and Neosapiens.

They join the Invaders from Infinity ( see List of Captain Marvel ( DC Comics ) enemies ) in their attempt to destroy the Solar System after being defeated, but are beaten and sent back to Mars while the Invaders are imprisoned and destroyed.

Therefore, the absence of life in Venus, with a somewhat similar composition to Earth's primitive conditions or the absence of life on Mars, given the proposed " resilience " of life in space, damages the panspermia theory, at least based on observations of our own Solar System-the theory suggests that life would be more abundant in the Solar system.

This is a collection of fifteen selected non-fiction entries that had been published in Analog magazine over the years ; it includes five articles authored or co-authored by Zubrin, including " The Hypersonic Skyhook ", " Mars Direct: A Proposal for the Rapid Exploration and Colonization of the Red Planet " ( co-authored with David A. Baker ), " Colonizing the Outer Solar System ", " Terraforming Mars " ( co-authored with Christopher McKay ), and " The Magnetic Sail ".

The term " Trojan " has come to be used more generally to refer to other small Solar System bodies with similar relationships to larger bodies: for example, there are both Mars Trojans and Neptune Trojans, and Saturn has Trojan moons.

The highest known mountain in the Solar System is Olympus Mons on the planet Mars at.

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter.

The first AI in space ( Deep Space 1 ) was developed from Code TI, as is the MAPGEN software that daily plans the activities for the Mars Exploration Rovers, the same core reasoner is used for Ensemble to operate Phoenix Lander, and the planning system for the International Space Station's Solar Arrays.

* Mars Series ( USSR ) Profile by NASA's Solar System Exploration

* C. S. Lewis wrote, in Out of the Silent Planet, about three humans visiting Mars and meeting three different kinds of native intelligent creatures ( sorns, ( or séroni ), hrossa, and pfifltriggi ) there, as well as hunting hnakra and meeting the Oyarsa, or eldil in charge of this planet, called Malacandra in the Old Solar language.

Earth's Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars.

MABTEX might be followed in turn by a small solar-powered blimp named MASEPA, for " Mars Solar Electric Propelled Aerobot ".

In 1984, a high priority mission to Mars was set forth by the Solar System Exploration Committee.

* Solar System in fiction: Real planets of the Solar System have that have been utilized or characterized in a variety of fictional ways ( e. g. Edgar Rice Burroughs ' Barsoom, a fictional version of Mars ).

The events of the revolution send Clarke ( and Boyle ) spinning off into the outer Solar System at the end of Red Mars ; Green Mars finds her back in the equation, but her influence is greatly reduced against the backdrop of a much-expanded UNTA presence.