Wyoming Skies for March

A monthly look at the night skies of Wyoming, written by Ron Canterna, professor in the University of Wyoming Department of Physics and Astronomy.

After sunset around 8 p.m. our Milky Way Galaxy becomes an ever present, hazy arch of unresolved stars stretching from the southeast horizon to the northern cardinal horizon point. Starting from the southern horizon, the plane of the Milky Way passes through the constellation Canis Major and the bright star of Sirius, Canis Minor, the twins Castor and Pollux of Gemini, Auriga and the yellowish-star Capella (the She-Goat), Perseus, and finally resting on the northern horizon at Cassiopeia (W-shaped).

The Orion nebula, the Pleiades, and the Hyades cluster of stars in Taurus the Bull (V-shaped) are placed to the southwest of the plane. Stars of various colors, like the reddish Betelgeuse in Orion, orange-colored Aldebaran (eye of the Bull), the bright-white Sirius low on the southeast horizon and the yellow star Capella can be seen in this spectacular display.

This month Venus becomes the evening star, Mars is in Gemini and present practically the entire night, while Saturn, located in Virgo, rises at 9 p.m. The first day of spring arrives March 20.

March 2010 Wyoskies Interest: Classifying the Orbiting Objects of the Solar System I.

Historically planets were those "star-like" objects in the night sky that moved relative to the stars. The major naked-eye planets, Mercury, Venus, Mars, Jupiter and Saturn, were seen and studied in ancient times. Later in the 19th and 20th centuries using telescopes and Newtonian physics, Uranus, Neptune and Pluto were discovered.

When the Earth is included, the traditional nine planets in the solar system were classified as terrestrial or "Earth-like" or Jovian or "Jupiter-like." But the solar system is a little more complicated after more recent discoveries in the 20th century. Planets were the big, spherically shaped bodies, the satellites or moons were various shapes and sizes but they orbited the planets, the asteroids were small dense bodies that orbit the sun independent of planets, and comets were icy non-spherically-shaped blobs orbiting the sun in highly eccentric orbits.

This was the standard picture of the solar system's major orbiting objects until modern space exploration and current discoveries upset this relatively simple picture.We will discuss these changes to our solar system's classification scheme in the next two Wyoming Skies columns.

For more information, visit the Wyoming Skies home page (http://wyoskies.uwyo.edu ) or send an e-mail to canterna@uwyo.edu.

Posted on Thursday, February 25, 2010

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