Starwatch Newsletter Minnesota Starwatch is a newsletter describing the night sky in the Midwest. It is updated monthly, and is produced by the Department of Astronomy, University of Minnesota 116 Church Street SE, Minneapolis, MN 55455

Hello, this is Minnesota Starwatch for June 2003.

June signals the start of summer in the northern hemisphere. Astronomically, summer begins this year on June 21st, precisely at 2:11pm Central Daylight Time; that is when the Sun reaches its northern-most position in the sky. The Sun's rays strike the Earth most directly in the northern hemisphere at local noon on June 21st. That date also corresponds to the longest period of daylight in our hemisphere during the year. Together these developments increase the amount of heating of the land, water and air around us, producing the warmest weather of the year over the summer months. Perhaps surprisingly, the Earth is actually slightly closer to the Sun in January than in June. It is the tilt of the Earth's spin, which points more towards the Sun in summer than in winter that is the main cause of seasons.

Just after twilight both Jupiter and Saturn can be seen in the western sky. Saturn is only about 10 degrees above the horizon and just north of west, so will take sharp eyes and a clear horizon to view. On June 1st the thin crescent moon may be visible just above Saturn. Jupiter is much better placed at the start of the month, being about 30 degrees above the western horizon at sunset. Mercury and Venus are low in the early morning sky above the northeast horizon for about an hour before sunrise.

Mars is on its way to becoming the planetary spectacle of the summer. By the end of June, Mars rises in the east a little after midnight. Its bright red glow should be unmistakable. By August Mars will be exceedingly bright as the Earth and Mars come about as close together in their orbits as they ever do. In fact, calculations indicate that this will be their closest approach in at least 50,000 years! All summer long Mars will be bright and easy to observe when it is in the sky. The rise time for Mars shifts slowly to earlier hours, so will be observable all night long by summer's end. Even binoculars or a small telescope will reveal Mars' planetary disk during this time.

On June 8th the first quarter moon will enter the constellation Virgo and pass just below a rich cluster of galaxies, known to astronomers simply as the Virgo Cluster. Those galaxies lie about 50 million light years beyond our own Milky Way. The cluster contains about 2000 galaxies, some even bigger than the Milky Way. Most galaxies live in groups or clusters. Our own galaxy is one of a group of about 30 galaxies we call "The Local Group." The Milky Way and the Andromeda Galaxy, about 2 million light years away, are the dominant galaxies in The Local Group. The Virgo Cluster is the closest rich cluster of galaxies. Many of its galaxies are visible in small telescopes. About 10 degrees north of Virgo in the constellation Coma Berenices is another, even more impressive galaxy cluster. This one is about five times farther away, however, so a modest telescope is needed to spot these galaxies. In recent years astronomers have realized that The Local Group, the Virgo Cluster and the Coma Cluster all belong to an even bigger structure called a "supercluster" of galaxies. These huge structures have been found at enormous distances, distributed like beads on strings in what astronomers call "cosmic filaments." All these structures are thought to form as a result of the long-range effects of gravity in the universe. By studying their distributions and other properties astronomers are learning important clues about the history of the universe.

For those interested in the Minnesota Astronomical Society, call 952-467-2426 for information their upcoming events.

Minnesota Starwatch is available on-line at http://www.astro.umn.edu/Outreach/pub_out.html

For fun Astronomy Outreach programs or how you can help build the new Minnesota Planetarium, please call 612-630-6151 or visit http://www.mplanetarium.org.

Como Planetarium is offering fun, family shows about astronomy on a limited basis, please call 651-293-5398 for more info!

This has been Minnesota Starwatch, produced by the University of Minnesota Astronomy Department.

Last Updated: Wed May 21 10:20:35 2003