Astronomy Concepts

ASTRONOMY CONCEPTS

Animation of electromagnetic waves.

Scientists have observed that electromagnetic radiation has a dual "personality." Besides acting like waves, it acts like a stream of particles (called "photons") that have no mass. The photons with the highest energy correspond to the shortest wavelengths.

electromagnetic spectrum with great info

Diagram showing the top of a wave is a crest, the
bottom is a trough.

A chart showing the electromagnetic spectrum.

THE SPEED OF LIGHT

What is a light year?

The Light Year: A Measure of Distance

The distance that light travels in a year is so large that it is a useful unit of distance in astronomy:

Light Year: the distance that light travels (through a vacuum) in one year (9.46 x 10^17 cm).
The nearest star (other than the Sun) is 4.3 light years away.
Our galaxy (the Milky Way) is about 100,000 light years in diameter.
The distance to the galaxy M87 in the Virgo cluster is 50 million light years.
The distance to most distant object seen in the universe is about 18 billion light years (18 x 10^9 light years).

Read this and then take a speed of light quiz

BIG BANG THEORY

Read an article about the Big Bang theory

Cosmic Timeline

What is the Big Bang Theory?

Check out questions regarding the Big Bang theory

Tests of the Big Bang: Expansion

Questions regarding the expansion of the universe

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Click below for information on The Doppler Effect.

COBE satellite map of the cosmic background radiation

Cosmic Background Radiation

Life Cycle of Stars

Check out Sky & Telescope for some interesting astronomy facts

Comet Hale-Bopp: Check out more pics of this comet

Check out The Comet Watch Program

THE SUN

Many facts about our yellow sun

Check out pictures of the sun from space

Click below for the layers of the sun

Layers of the sun

SOLAR ENERGY

What are sunspots?

Get daily sunspot summaries from NOAA

The SOHO satellite shows up to date sunspot activity

THE CONSTELLATIONS AND THEIR STARS

Take a virtual trip to a black hole and neutron stars

THE MOON

"I had the ambition to not only go farther than man had gone before, but to go as far as it was possible to go."
- Captain Cook

Strange Moon Facts

Virtual Moon Phases

Current Phases

	New Moon - The Moon's unilluminated side is facing the Earth. The Moon is not visible (except during a solar eclipse).
	Waxing Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.
	First Quarter - One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.
	Waxing Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.
	Full Moon - The Moon's illuminated side is facing the Earth. The Moon appears to be completely illuminated by direct sunlight.
	Waning Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.
	Last Quarter - One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.
	Waning Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.

Does the moon influence you??

TO THE MOON

Apollo 11 Facts

Apollo Landing - Was it a hoax?