why does the earth travel around the sun? the law of universal gravitation the strength of the...
TRANSCRIPT
OUR SOLAR SYSTEM
YOUTUBE - THE KNOWN UNIVERSE BY AMNH
Why does the Earth travel around the Sun?
THE LAW OF UNIVERSAL GRAVITATIONThe strength of the gravitational force between two objects depends upon the mass of the objects and the distance between them.
Earth travels around the Sun because it is trapped within the Sun’s gravitational force of attraction.
How do we measure distances in space? ….everything is so far away!!!
Light-year - The distance light travels in 1 year
Light travels at 300,000 km/s in space, so light travels 9.46 trillion km in one year It takes light from the Sun 8.3 minutes to travel to the surface of the Earth Closest star to our Sun, Proxima Centauri, is about 4 Light-years away Closest galaxy to our Milky Way, Andromeda, is about 2.5 million Light- years away The farthest objects we can observe are more than 10 billion Light-years away
Astronomical Unit (AU) – one AU is equal to the distance from the Earth to the Sun, or 93 million miles, or 150 million km
How are the planets of our solar system alike and different?Inner Planets• Mercury, Venus, Earth, Mars • dense and rocky surfaces• smaller than the outer planets•“terrestrial planets”
Outer Planets• Jupiter, Saturn, Uranus, Neptune • large and composed mostly of gases•all have rings• hold more moons due to increased gravitational force• “gas giants”
How are the planets of our solar system alike and different?Mercury has no atmosphere and no moons
Venus is the hottest planet due to the greenhouse effect of its CO2 atmosphere; it has no moons
Earth is 1 AU from the Sun and the only planet with liquid water
Mars is red due to the presence of iron in its soil
Jupiter is the largest planet with the most gravity
Saturn has the largest and most complex ice rings
Uranus has a very tilted axis of rotation
Neptune is the coldest planet with an average temperature of -200˚ C
What are dwarf planets?Dwarf planets are spherical objects that orbit the Sun, but they do NOT have more mass than the objects in nearby orbits; they are made of rock and ice and are smaller than Earth
http://chiawyuen99585.web.officelive.com/dwarf_planets.htm
What are Asteroids?
Asteroids – small rocky bodies • diameter– a few meters to >900 km in size• irregular shapes• orbit the Sun in the Asteroid Belt between Mars and Jupiter• asteroids can be rich in carbon, stony, or metallic• the small moons of other planets may be captured asteroids
Asteroids Mathilde, Gaspra , and Ida
What are Meteoroids?Meteoroids – small rocky bodies, smaller than asteroids• most are probably pieces of asteroids• if the meteoroid burns up in Earth’s atmosphere before it
hits the ground, we call it a meteor
• if a meteoroid enters Earth’s atmosphere and strikes the ground, we call it a meteorite
• meteor showers happen when Earth passes through the dusty debris that comets leave behind
• types of meteorites – stony, iron, and stony-iron
http://meteorites.asu.edu/meteorite-facts/what-different-types-are-there
What are Comets?
Comets (“dirty snowballs”) – small body of ice, rock, and cosmic dust loosely packed together• ice is heated when comet
passes close to the Sun, and comet gives off gas and dust in the form of a long tail
• many scientists think comets come from the Oort Cloud and Kuiper Belt
http://www.classbrain.com/artteensb/uploads/comet_diagram.gif
Comet Hale-Bop was visible in the sky from May 1996 through September 1997
http://apod.nasa.gov/apod/ap070331.html
The Kuiper Belt is a disc-shaped region beyond Neptune (30 – 50 AU). It contains comets. The Spitzer telescope observes these objects in the infrared.
http://www.nasa.gov/pdf/145944main_Kuiper.Belt.Lithograph.pdf
Pluto’s orbit
The Oort cloud extends out beyond the Kuiper Belt (50AU +) and contains comets. The outer edge of the Oort cloud is considered to be the edge of our Solar System.
Technology is essential to science in order to learn about space
Magellan Mission (1989) – mapped Venus and found volcanoes
Venera 9; Russian (1975) – 1st probe to land on Venus and found surface rocks similar to Earth, surface temperature of 464˚C, severe greenhouse effect
Viking 1 and 2 (1975) – probes had instruments to gather soil on Mars and test it for life
Mars Pathfinder Mission (1997) – sent back detailed images of dry water channels on Mars
Pioneer 10 and 11 (1972) – 1st probes to visit outer planets; sampled solar wind; Pioneer 10 traveled past Pluto (1983)
Galileo (1989) – arrived at Jupiter in 1995 and sent a smaller probe to measure Jupiter’s atmosphere; gathered info about moons
Voyager 1 and 2 – 1st probe to detect Jupiter’s rings; 1st to fly by 4 gas giants
Cassini Mission (1997) explored Saturn’s moons; deployed a smaller probe called Huygens to study the atmosphere of its Titan moon
Technology is essential to science in order to learn about space