The Planets in our Solar System

Solar System Basics Our solar system is not only made of the Sun, the nine planets and their satellites, but also asteroids and comets. All celestial bodies revolve around the sun.

The characteristics of each planet were determined by where each planet formed in relation to the Sun. The various temperatures created different elements. Heavier elements formed closer to the heat of the Sun, lighter elements formed farther from the Sun.

More on planet formation . . . Temperature and distance from the Sun influenced the condensation of various substances within the evolving solar system. Eventually, the condensing material merged to form large bodies hundreds of kilometers in diameter.

These bodies were called planetesimals. The planets began to form from the collision of these planetesimals.

To be or not to be . . . Pluto is weird  Planet: Solid surface but low density; the best of both worlds! Planet: Yes, solid body orbiting star. No, orbit too far off and not regular. Decide for yourself!!

The Birth of the Sun The sun formed from the dense concentration of gas at the center of the solar nebula. As the gas and dust condensed, the temperature and pressure at the center increased. The temperature and pressure became so great, nuclear fusion began.

The Sun (. . . Continued) Nuclear fusion causes lighter atoms, like hydrogen, to fuse and become heavier atoms, like helium. This reaction releases tremendous amounts of energy. The sun releases this energy in the form of thermal energy and light.

Other Objects in the Solar System Asteroids Small, rocky bodies that orbit the Sun. Comet A small body that revolves around the Sun in an elliptical orbit. It is a body of ice with a rocky core When it nears the Sun, the ice melts and is illuminated by the sun, forming the tail.

Meteoroids, Meteors, and Meteorites! A fragment of an asteroid that enters Earth’s atmosphere. Meteor A meteoroid that burns up as it enters Earth’s atmosphere. (Shooting Star) Meteorite A meteor that hits the Earth

Formation of the Planets The particles in space surrounding the sun contracted to form the planets of the solar system. *A planet is a celestial body revolving around a star. Our solar system has 9 planets revolving around our star – the Sun.

Two Types of Planets *Gas Giant Planet: The Inner Planets The Outer Planets Gaseous About 15 times larger than Earth Composed of hydrogen and helium Light, very low density Jupiter, Saturn, Uranus, Neptune The Inner Planets Terrestrial Made of heavy, solid elements Mercury, Venus, Earth, Mars

Galaxies . . . The sun is the star of our solar system, but it is only one of millions of stars in the Milky Way Galaxy. A *galaxy is a system containing millions of stars held together by gravity.

The Neighborhood . . . *A Local Group of galaxies is a group of 30 galaxies, of which the Milky Way is a part. The local group is part of a 10,000 unit supercluster

Proxomity *Astronomical Unit (AU) The distance between the Earth and the Sun ~ 93 million miles. A *light year is the distance light travels in one year. ~ 9.7 trillion km.

General Solar System Info . . . (#1) The two largest planets in our Solar system are Jupiter and Saturn ~ both gaseous planets. (#2) Venus is the planet closest in size to the Earth.

(#3) The inner, terrestrial planets are much smaller than the outer, gaseous planets. (#4) According to the ESRT, Jupiter’s diameter is about 11 times greater than Earth’s.

(#5) The sun’s diameter is 1,394,000 km (#5) The sun’s diameter is 1,394,000 km. If we used the scale 1 mm = 700 km, the sun would be almost 2000 mm (1.9 m)! (#6) The outer planets are much farther apart than the inner planets.

(#7) The planets that are closest to Earth are Mars and Venus. (#8) Which planet has the longest period of revolution? Neptune at 165 years. Why? Check out the ESRT; It’s the farthest planet from the sun!

(#9) Which planet has the longest period of rotation? Venus 243 days Earth rotates in 24 hours! (#10) How many moons orbit around Jupiter? 16, compared to 1 for Earth, 18 for Saturn and 21 for Uranus!

Conclusion . . . All of the planets, including Jupiter, are dwarfed by the size of the sun The Earth is close to the sun in comparison to other, “nearby” stars and galaxies.