Tuesday, March 31, 2009

April eNewsletter from the Minnesota Planetarium Society

PARTICIPATE IN 100 HOURS OF ASTRONOMY, THURSDAY APRIL 2

In this issue from the Minnesota Planetarium Society

Board Chair Message
International Year of Astronomy event April 2
Extrasolar Planets
The Equinox
April Skies
Venus Occultation

Candidate Nominated for President
I am delighted to announce that the MNPS Board has voted unanimously to recommend a candidate to be our new president.  The name and other information will be released as soon as all the details can be worked out. This is an exciting time for us so stay tuned for a special edition of the MNPS ENews with more details.

Peggy Leppik, MNPS Board Chair

100 Hours of Astronomy
Thursday April 2, 5-9 p.m.
Anoka-Ramsey Community College Gymnasium
11200 Mississippi Blvd NW
Coon Rapids, MN 55433-3470

One of the key goals of 100 Hours of Astronomy is to have as many people as possible look through a telescope between April 2-5, as Galileo did for the first time 400 years ago.  Celebrate with the Anoka-Ramsey Community College Astronomy Club, UM Astronomy Outreach Program, Minnesota Astronomical Society, and Minnesota Planetarium Society.
Events: Hands-on astronomy and science activities, night-sky observing, and ExploraDome planetarium shows. Also, Robert Gehrz, Chair of the University of Minnesota's Astronomy Department, will be speaking about the upcoming SOFIA mission.
All events are free.

www.an.cc.mn.us/news/story_601.cfm
www.100hoursofastronomy.org/

ExploraDome Highlights Planets Around Other Stars
Perhaps you have visited our ExploraDome, and seen the location of other stars with known planets. Since 1995 over 300 “exoplanets” or extrasolar planets have been discovered. That number will jump dramatically thanks to NASA’s Kepler Mission, launched March 6th, 2009. Kepler will “stare” at the same 100,000 stars in the constellations of Cygnus and Lyra for the next 4 years, in a quest for new planets.

Most of the planets discovered so far are gas giants the size of Jupiter or larger. Of particular interest are planets similar to Earth in size, and orbiting in a habitable zone just the right distance away from their host stars. One star called Gliese 581c has an exoplanet that may support liquid water. The Kepler mission will shed light on whether Earth like planets are common in the universe and when new exoplanets are discovered, the ExploraDome will be the place to see just where they are located in the universe.

For more information:
NASA’s Kepler Mission   kepler.nasa.gov
PlanetQuest   www.planetquest.org
Exoplanet Catalog   www.exoplanet.eu

If you haven't seen the exoplanets in the ExploraDome, visit our webiste to schedule a visit:
www.mplanetarium.org/exploradome.htm

or to see when the ExploraDome will be open to the public:
www.mplanetarium.org/newsevents.htm

Does Equinox Mean Equal Day and Night?
Although the threat of snow is still with us in Minnesota, it's officially Spring, as of 6:44am on Friday March 20. However, if you were tracking sunrise and sunset times, you would have found the length of the day to be approximately 12h and 10m, longer than the 12h expected from the astronomical name for this day, the vernal "equinox" (equal day and night). 

Here's why the day is longer than you might think.  Consider a point in the middle of the Sun. IF there were no atmosphere, you would see that point rise and then set almost exactly 12h later on the vernal equinox. However, daylight is when sunlight first appears (when the top of the Sun just starts rising above the horizon) until the sunlight disappears (when the trailing edge of the Sun falls below the horizon), so that lengthens the day.  Even more important is that the atmosphere bends/refracts the light from the Sun, so that we can actually see it when it is still *below* the horizon.  This makes the time the Sun is visible even longer, giving us an extra 10 minutes of daylight.

For a fuller description and some nice graphics, see
news.nationalgeographic.com/news/2009/03/090319-vernal-equinox-2009-spring_2.html,
and enjoy the Spring!

April Sky Highlights
Around 10pm in April, Orion and friends (Sirius, Procyon, Castor and Pollux) are departing in the southwest sky. Leo dominates the southern sky. Look for his backwards question mark (The Sickle) which is his head about 60 degrees above the southern horizon. The bright star Regulus at the bottom of the sickle is his heart. About 15 degrees left of the sickle lies Leo’s hindquarters, a right triangle of stars. Saturn shines brightly about 7 degrees below the triangle. The Big Dipper is now high in the northeast sky. Follow the curve of the handle to “arc to Arcturus”, a red giant star about 20 degrees above the eastern horizon. Can you notice its slight difference in color? On April 22 at about 7:39 am, the Moon glides in front of Venus.

For star charts see:
skymaps.com
heavens-above.com

Watch Venus disappear behind the Moon
On the morning of April 22, the Moon will "occult" or move in front of Venus, as viewed from Earth.
In the Twin Cities, starting around 7:30 am look for the thin crescent Moon low in the southeast.  Use binoculars to locate Venus, which will look like a star just below and to the left of Venus.  Keep watching until Venus disappears at 7:39 am. Venus will reappear at 8:32 am.
If you are outside of the metro Twin Cities, use this website to find the timing at your location:
www.lunar-occultations.com/iota/planets/0422venus.htm