Astronomy 101

STAR Test Info

Our Universe

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Our Universe

• Estimated to be ~ 14 billion years old (#bigbang)
• Evidence:
• Speed of distant galaxies moving away from us
• Cosmic background radiation.
• Expansion after Big Bang; slowing and cooling now (?)
• Most of the universe is dark matter/ dark energy (?)
• Future - Big Crunch? or Expand Forever?

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Minute Physics Video (4:00)

Gravity

• Gravity plays a big role in the SHAPES of objects in the universe.
• It gives shape to the orbits of the planets, solar system, and even galaxies.
• The Sun’s gravity reaches the solar system and beyond, keeping the planets in their orbits.
• Gravity from Earth keeps the Moon and human-made satellites in orbit.

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Recall Inertia 1st!

Motion

Rotation (Day/Night)- Spin on axis. (about 24 hours). Tilted Axis (23.5⁰) reason for the seasons.

Revolution - Years (about 365 days). Orbits the sun (elliptical)

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Earth’s mean orbital velocity is about

30 km/sec

Types of Galaxies

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Stars make Light

Huge spheres of glowing gas.

Nuclear Fusion is why a star shines!

[H] + [H] = [He] + light

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Need High Temp & Pressure for Fusion.

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Sun’s Core ~ 15 million ⁰C

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Star Types

All stars begin their life in a nebula.

Our Sun has a diameter of 1.4 million km

Betelgeuse (supergiant) has a diameter of 420 million km.

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Distances

1 kilometer (km) = 1,000 meters (m)

1 km = 0.62 miles or 1 mile = 1.6 km

MVMS to Tam is about ½ a mile.

1 AU (Astronomical Unit) = 93 x 10⁶ miles

1 AU = 150 x 10⁶ km

Light Year = 9.5 x 10¹² km

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Our Solar System

Planet - “wanderer”

Moons are natural satellites.

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To Scale: Solar System Video (7:06)

Meteroid

A meteoroid is a chunk or rock or dust in space. They come from comets or asteroids.

Comet - Loose connection ice, dust, small rocks. Long & narrow orbit

Asteroid - Small rocky objects revolving around the Sun. Too small & numerous to be planets.

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Feb 2013 Russian Meteor.

Inner Rocky Planets

“Terrestrial”

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Not Drawn to Scale. Page 553

Outter Gassy Planets

• Jupiter-Largest (318 x Earth’s mass), many moons, Great Red Spot (300 year old storm), 10 hour days & 12 years to orbit sun, Hydrogen sludge ocean
• Saturn-Numerous rings and moons, least dense, year is 29 Earth years
• Uranus-Tilted on its side, retrograde motion (night can last 40 years), ice giant, many moons
• Neptune-violent storms (1,200mph), many moons, 165 Earth years to orbit, methane gas atmosphere

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Not Drawn to Scale. Page 563

Kuiper Belt

• Doughnut-shaped region past Neptune, where many comets originate.
• Contains many small, icy bodies.
• Pluto lives here.

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Cool Sites & Videos

• Earth & the Solar System. (7:29) - Bozeman NGSS - ESS1B
• http://solarsystem.nasa.gov/kids/#
• How do we study the stars? (4:45) - TEDEd
• Where did Earth’s water come from? (3:52) TEDEd
• Reasons for the seasons. (5:20) TEDEd
• Can we survive the Sun’s death? (3:36) - ASAP Science
• Hubble Site.
• Tour the Solar System from Home (7:53) - TED.com

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STAR Test Sample Problems

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FYI - one light year is

9.46 x 10¹² km

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