astronomy: solar system. the solar system consists of the sun, 8 planets, and their moons, and...
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Astronomy: Solar System
The Solar System• Consists of the sun, 8 planets, and their moons, and
several kinds of smaller objects that revolve around the sun
Our Solar System’s Only Star:
Only one star
• The Sun is the only star in the solar system
• The sun's light takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface.
• About 109x the size of Earth
The Sun:
• The Sun is a medium sized star
• There are giant stars that are 100x larger than the sun
Our sun in comparison to other stars:
What is a planet? 3 Criteria: 1) An object that orbits a star2) Large enough to become rounded by its own gravity3) Able to clear its own orbit of objects, such as asteroids, meteoroids, other space junk!
The Solar System• The 4 inner planets
(Mercury, Venus, Earth, and Mars) are called terrestrial planets • The outer planets (Jupiter,
Saturn, Uranus, and Neptune) are called gas giants
Relative Sizes of the planets:
Venus MarsMercury
Jupiter Saturn
UranusNeptune
Earth
On your notes, put the planets in order from largest to smallest
Relative Sizes of the planets:
1) Jupiter2)Saturn3)Uranus4)Neptune5)Earth6)Venus7)Mars8)Mercury
Planet Actual Distance from Sun (km)
Mercury 57,900,000
Venus 108,200,000
Earth 149,600,000
Earth’s Moon (Distance from Earth)384,403
Mars 228,000,000
Jupiter 778,400,000
Saturn 1,426,700,000
Uranus 2,866,900,000
Neptune 4,486,100,000
Relative Distances of the planets:
The Earth
• Earth is the third planet from the Sun • Is the largest of
the terrestrial planets
The Moon•Earth’s only natural
satellite •The Moon is in
synchronous rotation with Earth (the same side is always facing the Earth)
The Moon• Size: 3,476 km in diameter
(a little less than the distance across the United States)
•Distance from Earth: 384,403 km (110x the distance across the United States)
The Other planets also have moons:
Planet Number of moons
Jupiter 60+Saturn 31+Uranus 25+Neptune 13+
What’s with Pluto?1. The object must be in orbit around the Sun.
Well, Pluto does that!2. A "planet" has to be big enough that gravity
squeezes it into a round shape. Well, Pluto does that.
3. A planet must be big enough that it's gravity removes other objects that occupy the same orbit.
But Pluto does not meet this criterion.
Poor Pluto…
So, Pluto is considered to be a DWARF PLANET
Plutoids
• A name given for Dwarf planets (like Pluto) beyond Neptune
Asteroids• Rocky objects that are too
small (1-100 km in diameter) and too numerous to be considered planets
• They revolve around the sun in the asteroid belt (between the orbits of Mars and Jupiter)
• Have elliptical orbits
Comets
• Loose collections of ice, dust, and rocky particles
• Revolve around the sun in a very long, narrow elliptical orbit
• Most comets are found in the Kuiper belt (extends beyond Neptune’s orbit) or the Oort cloud
• Main parts: nucleus, coma, and tail
Meteoroid• Chunk of rock
or dust in space
• Come from comets or asteroids
Meteors
• When a meteoroid enters Earth’s atmosphere, friction with the air creates heat and produces a streak of light in the sky called a meteor
Meteorite
• If a meteoroid does not burn up completely, it passes through the atmosphere and hits the Earth’s surface and is called a meteorite
Put the following space objects in order from LARGEST to SMALLEST:
PlanetAsteroidStar Moon
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