The Modern Astronomer Glossary

Contained here is the combined knowledge of the entire Modern Astronomy staff.

Well not really.  But what is here is an easy to digest listing of the most common astronomical terms that might still be a bit puzzling to the learning amateur astronomer.  When applicable there are links to our own articles about the subject, or an external resource that we think is just truly the bee’s knees when it comes to educating our readers.

Hope this helps!

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Magnitude

Magnitude is the apparent brightness of a star to an observer on earth.  The Sun is the brightest star in the sky and has a blinding magnitude of -27.  The dimmest stars that can be seen with the naked eye are around 5th magnitude (notice the positive, not the negative number in front).  A 1st magnitude star is very bright.  Read this article by EarthSky.org to get the full details.

Scintillate

The slight twinkling that stars do. This is caused by disturbances in the earth’s atmosphere.

zodiac constellations

Twelve most commonly known constellations. These are the zodiac constellations because the sun is known to pass through this band of sky along with other solar system bodies like the planets and the moon, and these twelve constellations make up the “zoidiakos kyklos” or the circle of animals. They are zodiac because depending on where the sun was on the date of your birth would determine your astrological sign. Not astronomical. These constellations are Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, and Aquarius.

ecliptic

the apparent path that the sun travels through the sky through the year. Greek ekleiptikos for “the path which eclipses occur”.

inferior planets

also the interior or inner planets, these are the terrestrial planets that lie closer to the sun than the asteroid belt. These are Mercury, Venus, Earth, and Mars.

superior planets

also the exterior or outer planets are the gaseous planets Jupiter, Saturn, Uranus and Neptune.