Post on 11-Jan-2016
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 – 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!
• Meteoroids– 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
• The Inner Planets– Terrestrial
– Made of heavy, solid elements
– Mercury, Venus, Earth, Mars
• *Gas Giant Planet:– The Outer Planets
– Gaseous
• About 15 times larger than Earth
• Composed of hydrogen and helium
– Light, very low density
– Jupiter, Saturn, Uranus, Neptune
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. 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.