Go Stargazing: April Edition

Saturn dominates April 2011 skies because yesterday, on April 3, the Earth passed between the sun and Saturn.  This alignment, called opposition, puts Saturn in the sky all night long; it rises in the east at dusk and sets in the west at dawn.

Venus’ apparition as a dazzling morning star is coming to an end.  It is getting lower and lower in the sky each morning as the angle between the solar system plane and the horizon gets shallower.  Face southeast at dawn, and you can’t miss it of you have a clear horizon.

Jupiter is directly behind the sun from our perspective on April 6 and therefore invisible all month.

Mars also remains lost in the sun’s glare all month.

A swath of brilliant winter stars continues to dominate evening skies.  These stars are now high in the west at dusk and set in late evening.  Orion, the Hunter, is in the southwest as April begins.  His two dogs, represented by Sirius and Procyon, are to his left.  Beside Orion in the west is Taurus, the Bull with Aldebaran as its eye. Gemini, the Twins, are above Orion.  The Big Dipper is to the upper right of the North Star, with its handle pointing down and to the right.  From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are low in the east at dusk.  Leo, the Lion, passes almost overhead in late evening.

Below Sirius, just above the southern horizon in late twilight, is a star second only to Sirius in brightness.  This is Canopus, which marks the keel (bottom) of the legendary ship Argo Navis.  Canopus is so far south, in fact, that most Americans never see it.  From the Gulf Coast, however, Canopus does rise.  In early April, you can still see it in the evening just after dusk.

Creative Commons License photo credit: ComputerHotline

Moon Phases in April 2011:

New Moon                      April 3, 9:32 a.m.

1st Quarter                     April 11, 7:05 a.m.

Full Moon                       April 17, 9:43 p.m.

Last Quarter                  April 24, 9:46 p.m.

Sunday, April 24, is the first Sunday after the first Full Moon of spring.  Therefore, this is Easter Sunday.  This happens to be the second latest possible date for Easter.  Easter will fall on April 25, the absolute latest date, in 2038.

Go Stargazing! March Edition

Saturn is up all night long by month’s end.  On Mar. 21, Earth passes between the sun and Saturn.  This alignment is called opposition because it puts Saturn and the sun on opposite sides of the Earth.  As a result, Saturn rises at dusk and sets at dawn on this date.  Look for Saturn to rise due east around 8:00 p.m. tonight. It will rise just a little bit earlier each night.

Venus enters the evening sky by the end of March.  As March opens, Venus is still setting during twilight, making it hard to notice at dusk.  By the end of the month, though, Venus has come out from behind the sun far enough for us to notice it clearly.  Face west at dusk and look for a point of light that outshines everything in the sky but the sun and the moon.

Mars has become an evening object.  It is now already up in the east-northeast by dusk.  On Jan. 29, Mars came to opposition as Earth passed between Mars and the sun, putting Mars in our sky all night long.  Earth is now pulling ahead of Mars on its faster orbit.  As a result, Mars is slightly dimmer each night for the rest of 2010.  However, during March, Mars remains brighter than average, and thus remains easy to see.  Look high in the southeast as dusk (due south by the end of the month) for a reddish point of light sort of in line with the two Dog Stars 

Jupiter is mostly out of sight this month.  Viewers with a very clear east-southeast horizon may notice Jupiter low in the sky at dawn by the end of March.  

Creative Commons License photo credit: kevindooley

Dazzling Orion is high in the south.  His belt points up to Aldebaran, the eye of Taurus, the Bull.  The Dog Stars Sirius and Procyon are to Orion’s left.  Sirius is the brightest star we ever see at night.  Gemini, the Twins, are to Orion’s upper left.  Look for two stars of equal brightness less than 5 degrees (three fingers at arms’ length) apart.  These are Castor and Pollux, marking the twins’ heads.  High in the northwest is Capella, the sixth brightest star ever seen at night.  At dusk on March evenings, look below Sirius and a bit to its right for Canopus, the second brightest star we ever see at night. This star is in the keel (bottom) of the legendary ship Argo.  Canopus is so far south that most Americans never get to see it.  We, however, are far enough to the south that it barely rises for us, remaining low on the southern horizon.  

Meanwhile, spring stars are rising in the east.  A distinct backwards question mark shape outlines the mane and forepaws of Leo, the Lion.  Three stars forming a right triangle rise underneath; they mark Leo’s hindquarters.  The Big Dipper is once again fully risen at dusk. Later in the evening, you can extend its handle to ‘arc to Arcturus’ and then ‘speed on to Spica’.  These stars will be along the eastern horizon by 9:30 tonight, and even earlier later in the month.

Transit Lune/Saturne du 22 mai 2007
Creative Commons License photo credit:

Moon Phases in March 2010:

Last Quarter                  March 7, 9:43 p.m.

New Moon                      March 15, 4:02 p.m.

First Quarter                  March 23, 5:59 a.m. 

Full Moon                        March 29, 9:25 p.m.

At 12:33 p.m. on Saturday, Mar. 20, the sun is directly overhead at the equator.  This, then, is the vernal equinox. On this date, everyone in the world has the same amount of daylight and the same amount of night.  After this date, daytime is longer than night in the Northern Hemisphere, while night is longer than daytime in the Southern Hemisphere. 

Sunday, Mar. 14, is the second Sunday in March.  Accordingly, we spring forward into Daylight Saving Time at 2 a.m. that morning (1:59:59 a.m. is followed by 3:00:00 a.m.).  Don’t forget to set your clocks forward by one hour before going to bed Saturday night!