Solar System

Asteroids are small solar system bodies that are not comets, especially those of the inner Solar System. They have also been called planetoids, especially the larger ones. 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. They are grouped with the outer bodies—centaurs, Neptune trolians, and trans-neptunian objects—as minor planets, which is the term preferred in astronomical circles. This article will restrict the use of the term "asteroid" to the minor planets of the inner Solar System.

Asteroids

CometsA comet is an icy small solar system body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus. Comet nuclei range from a few hundred meters to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. Comets have been observed since ancient times. Comets have a wide range of orbital periods, ranging from a few years to hundreds of thousands of years. Short-period comets originate in the Kuiper belt, or its associated scattered disc, which lie beyond the orbit of Neptune. Longer-period comets are thought to originate in the Oort cloud, a hypothesized spherical cloud of icy bodies in the outer Solar System. Long-period comets plunge towards the Sun from the Oort cloud because gravitational perturbations caused by either the massive outer planets of the Solar System (Jupiter, Saturn, Uranus, and Neptune), or passing stars. Rare hyperbolic comets pass once through the inner solar system before being thrown out into interstellar along hyperbolic trajectories. Exocomets, comets beyond our solar system, have also been detected and may be common in the Milky Way Galaxy.

MeteoroidsA meteorite is a meteoroid originating in outer space that survives impact with the Earth's surface. A meteorite's size can range from small to extremely large. Most meteorites derive from small astronomical object called meteoroids, but they are also sometimes produced by impacts of asteroids. When a meteoroid enters the atmosphere, frictional, pressure, and chemical interactions with the atmospheric gasses cause the body to heat up and emit light, thus forming a fireball, also known as a meteor or shooting/falling star. The term bolide refers to either an extraterrestrial body that collides with the Earth, or to an exceptionally bright, fireball-like meteor regardless of whether it ultimately impacts the surface.More generally, a meteorite on the surface of any celestial body is a natural object that has come from elsewhere in space. Meteorites have been found on the moon and Mass. Meteorites that are recovered after being observed as they transited the atmosphere or impacted the Earth are called falls. All other meteorites are known as finds. As of February 2010, there are approximately 1,086 witnessed falls having specimens in the world's collections. In contrast, there are over 38,660 well-documented meteorite finds.

Halley’s cometHalley's Comet or Comet Halley, officially designated 1P/Halley , is the best-known of the short-period comets and is visible from Earth every 75–76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime. Other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years.Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BCE. Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. Halley's Comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061.

Halley’s comet

Gallery

The Question Bank

1. What are asteroids also called ?2. How are asteroids?3. From where do short period comets originate?4. What is the Oort cloud?5. What do we otherwise refer to meteors as?6. From where do Meteors become visible?7. What does the term Bolide refer to ?8. What are falls?9. What is the official designation of the “Halley’s Comet”?10.When did the “Halley’s Comet” appear last and when will it

appear next?

1. Planetoids.2. Asteroids are usually Rocky or metallic.3. Short-period comets originate in the Kuiper belt, or its associated scattered

disc, which lie beyond the orbit of Neptune.4. Longer-period comets are thought to originate in the Oort cloud, a hypothesized

spherical cloud of icy bodies in the outer Solar System.5. Shooting Stars.6. Meteors become visible at about 75 to 120 kilometers above the Earth’s surface.7. The term Bolide refers to any extraterrestial body or a meteor that hits or doesn't

hit the earth’s surface

1. Planetoids2. Asteroids are generally rocky or metallic3. Short-period comets originate in the Kuiper belt, or its

associated scattered disc, which lie beyond the orbit of Neptune.

4. Oort cloud is a hypothesized spherical cloud of icy bodies in the outer Solar System.

5. Shooting stars6. They become visible at about 75 – 120 kms from the Earth.7. The term Bolide refers to any extraterrestial body that collides

with the earth or to an exceptionally bright meteor regardless of whether it ultimately impacts the earth.

8. Meteorites that are recovered after being observed as they transited the atmosphere or impacted the Earth are called falls.

9. The official designation of Halley’s comet is 1P/Halley.10.Halley's Comet last appeared in the inner Solar System in 1986

and will next appear in mid-2061.

Presented By R.Rajesh

Ritesh

Rohan

Roshan

SachinKrishna