Astronomy 101
Analemma
Ever notice on globes of the Earth there is a figure 8
printed in the middle of one of the oceans?
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Asteroids
The majority are between the orbits of Mars and Jupiter.
This region is known as the Asteroid Belt.
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Aurora
Auroral activity strongly correlates with solar activity. Peak activity repeats
on an 11-year cycle.
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Big Bang
The explanation is widely accepted today. It was critics of the interpretation
who coined the name.
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Black Holes
A region of space where the force of gravity is so intense that
not even light can escape.
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Bode Titius
Bode and Titius, reported a numerical sequence into which the sizes of the planetary orbits fit.
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Brightest Stars
A list of the 20 brightest stars in the sky, with their names,
magnitudes, and distances, etc.
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Comets
Big dirty snowballs made of ice, dust and bits of rock, and
are about the size of cities and towns.
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Constellations
The sky is divided into 88 parts. They
are sometimes grouped into 8 distinct families or groups.
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Coordinates
Two primary ways to describe a position in the sky. The Horizon System,
and the Equatorial System.
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Cosmology
Terms used in cosmology, which is the study of
the beginning and the evolution of the Universe.
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Cruithne
An asteroid with a bizarre orbit. It appears to make a series of bean shapes which
form a horsehoe.
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Dark Matter
Astronomers estimate that most matter is of some form that is impossible to detect directly.
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Eclipses
Alignments of the Sun, Moon, and Earth, resulting in dramatic large scale shadow play.
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Galaxies
Collections of stars, dust and gas, and other matter. Containing
between millions and trillions of stars.
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Historical Figures
The giants of astronomy over the last 2000 years
have guided and shaped our view of the cosmos.
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HR Diagram
The "Rosetta Stone" of stellar astronomy. It plots a star's luminosity against its surface temperature.
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Hubble's Law
The motion of the galaxies in the Universe appears to
be a smooth recession away from each other.
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Intelligent Life
Is anybody out there? Why would
they come all that way to make circles in our crops?
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Kepler's Laws
Kepler is remembered for "cracking the
code" that describes the orbits of the planets.
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Kuiper Belt
A region beyond the planets of the outer solar system which contains thousands of icy bodies.
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Leap Year Rules
Years perfectly divisible by four,
except years which are both divisible by 100 and not divisible by 400.
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Light Waves
Light radiates from a source in waves. Each wave has two parts; an electric part,
and a magnetic part.
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Lunar Libration
Over time we can see more than 50% of the Moon's surface from Earth
due to a combination of effects.
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Messier Objects
The french astronomer cataloged deepsky objects.
Considered showpieces for deepsky enthusiasts.
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Meteors
Sometimes called "shooting stars," most are
bits of gravel the size of your fingernails or smaller.
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Milky Way
Billions of stars too far away to pick out
individually but together they add up to a haze across the sky.
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Moon
A detailed Moon map, moon facts, lunar formation theories,
and an audio clip of the first landing.
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Moon Phases
As the Moon orbits we see varying combinations
of the lighted and the dark parts of the surface.
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Planets
Large bodies of mass that orbit around a star, like several
that reside in our own solar system.
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Precession
The position of the Sun on the vernal equinox is slowing
shifting westward across the sky.
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Rainbows
There are a variety of optical effects possible when light shines onto
moisture in the atmosphere.
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Redshift
A light source spectrum is seen as blueshifted as it
approaches, and redshifted as it moves away.
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Seasons
The tilt of Earth's axis
relative to its orbit,
not differences in the distance to the Sun.
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Stardust
Dust is a relative newcomer to the Universe. It joined gases
after some of the first stars exploded.
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Stellar Evolution
Stars begin as offspring of a cloud up to 300 light-years across.
Such a cloud is known as a nebula.
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Sun & Fusion
The Sun has layers with different properties,
about 75% hydrogen and 25% helium.
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Telescopes
The size and quality of the
objective element is the most important consideration. Bigger is better.
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Tides
Why are there two high tides and low tides
every day, the Moon passes overhead once per day?
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Time of Day
Universal Time, time zones, daylight savings time,
sidereal time, Julian Day numbers, and more.
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Twilight
Three types; civil, nautical, and astronomical, are defined
by the position of the Sun.
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Zodiac
The circle of animals along the ecliptic, the path described
by the Sun during the course of a year.
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