Unit-5 The universe

By Diego G.,Mariana,Sandra and Anderson

Satellites

Satellites are smaller celestial bodies that orbit the planets. The moon is the Earth’s only satellite,but Jupiter has more than sixty!

Dwarf planets.(Pluto and the Earth.)

Dwarf planets are spherical bodies that orbit the Sun.They are much smaller than planets.Until 2006,astrologers considered Pluto to be a planet , but now it is classified as a dwarf planet.

Small Solar System bodiesA small Solar System body (SSSB)is an

object that is neither a planet nor a dwarf planet.This group includes asteroids and comets.

Small Solar System bodies

Asteroids are small,rocky objects that orbit the Sun.They are mostly found in two regions :

The asteroid belt, between Mars and Jupiter,and the kuiper belt,beyond Neptune.

Comets

Comets are giant balls of ice. They orbit the Sun in a long,elliptical path.When they get close to the Sun,they show a bright tail that reflects light. Halley’s Comet is the best known. It can be seen every 76 years. It last appearance was in 1986.

Sometimes,asteroids and comets crash into a planet. The impact of these large bodies can have serious consequences.Scientists believe that a giant asteroid collided with Earth 65 million years ago. This changed the Earth’s climate and may have caused the extinction of the dinosaurs.

Shooting stars.

When small celestial bodies the size of dust particles burn up as they enter the Earth’s atmosphere ,we see shooting stars.

Meteorites

Meteorites are bodies that are too large to burn up completely,so they crash into the Earth.

Asteroid Ida 243

Asteroid ida 243 is located in the asteroid belt between Mars and Jupiter. It is 58 kilometers long.

The meteor crater in Arizona.

The meteor crater in Arizona is the best preserved meteorite crater on Earth. It was created 50,000 years ago when a 50 m diameter meteorite crash into the Earth.

The Leonid Meteor Shower

Shooting stars. The Leonid Meteor Shower of shooting stars.It occurs when debris from the comet Tempel-Tuttle crosses the Earth’s path. Most shooting stars are really rocks that burn up as they enter the Earth’s atmosphere.

Question…

What type of celestial body is shown in each picture?

Comet Asteroid

+information :About dwarf planets

+information In 2006 the International Astronomical Union adopted the

term ‘dwarf planet’ for solar system objects that were bigger than small solar system bodies such as comets and asteroids but not quite planets.

The definition of a dwarf planet is an object orbiting the Sun that is large enough to be rounded by its own gravity but is not gravitationally dominant in its orbital area and is not a moon.

As of 2008, there are five recognized dwarf planets: Pluto, Ceres, Eris, Makemake & Haumea.

There are a number of other candidates for the status of dwarf planet. Some of these classifications could be resolved as NASA’s Dawn and Horizon missions venture towards Pluto in the coming years.

Pluto

PlutoPluto hit the headlines in 2006 when it

was demoted from a planet to a dwarf planet by the International Astronomical Union. While most astronomers agreed with the new classifications, some disagreed and still refer to Pluto as the ninth planet.

Ceres

CeresCeres is located in the asteroid belt

between the orbits of Mars and Jupiter. It was discovered in 1801, well before Pluto and 45 years before Neptune. Ceres was considered a planet for around 50 years before being reclassified as an asteroid and once again in 2006 as a dwarf planet

Eris

ErisEris was discovered in 2005 and was

referred to as the tenth planet until it was reclassified in 2006. It is the largest of the dwarf planets

Makemake and Haumea

MakemakeMakemake was discovered in 2005 and

the third largest dwarf planet behind Eris and Pluto.

HaumeaHaumea was discovered in 2004 and

named a dwarf planet in 2008.

Page 57. Unit-5.