Go Stargazing! April Edition

night-sky-2
 Creative Commons LicensePhoto Credit: myyorgda

Saturn was up all night last month, and will remain well placed in the evening sky this month.  You can spot it in the east at dusk.  Mercury is briefly visible at dusk in late April.  Mercury is nowhere near as dazzling as Venus, but is bright enough to appear in twilight while most stars aren’t.  Look low in the west northwest at dusk, right over the point of sunset, beginning mid-month.  Mercury appears farthest from the Sun on April 26; the crescent moon that night will help you find it. 

Jupiter, in the southeast at dawn, is the brightest thing in that part of the sky (Venus is brighter but is located due east) unless the Moon is nearby (as it is on April 19).  Mars remains close to the horizon at dawn much of the spring, and takes longer to fully emerge into the morning sky.  Venus can help you find Mars towards the end of the month.  Beginning about mid-month, Mars appears to the lower left of the much brighter Venus.  Mars appears under Venus (between Venus and the horizon) on April 27.

Venus enters the morning sky in dramatic fashion this month.  Look due east right as day begins to break for the brightest thing there except for the Moon.  You’ll see Venus noticeably higher in the sky each passing day.   On the morning of April 22, the crescent Moon is very close to Venus.  In fact, the Moon actually occults (blocks) Venus shortly after sunrise that morning.  Venus remains the ‘morning star’ for the rest of 2009.  

Dazzling Orion shifts westward now that spring is underway.  His belt now points up right Aldebaran, the eye of Taurus, the Bull, which sets with Orion in the west.  The Dog Stars Sirius and Procyon are also found in the west, to Orion’s left.  Sirius is the brightest star we ever see at night.  Now above Orion are two stars of similar brightness less than five degrees apart.  These are Castor and Pollux, marking the heads of Gemini, the Twins. 

full-moon
 Creative Commons LicensePhoto Credit: myyorgda

Look in the east at dusk for stars in the shape of a backwards question mark, with a right triangle below that.  These stars are in the constellation Leo the Lion.  Saturn rises in Leo.  The Big Dipper is highest on spring evenings.  From the Big Dipper’s handle, you can ‘arc to Arcturus.’  Arcturus, in the east at dusk, is the fourth brightest star we ever see at night and will be the brightest one in the sky once Sirius sets. Continuing the curve of the Big Dipper’s handle past Arcturus, you can ‘speed on to Spica, a star low in the southeast at dusk.  Spica represents a stalk of wheat held by Virgo, the Virgin, who is in fact the harvest goddess.

Moon Phases in April 2009:

First Quarter                     April 2, 9:33 am
Full Moon                          April 9, 9:55 am
Last Quarter                     April 17, 8:38 pm
New Moon                         April 24, 10:23 pm

Easter is the first Sunday after the Paschal Full Moon, which is the first moon whose 14th day is on or after March 21 (the  “vernal equinox“).

Go Stargazing! December Edition

The ‘main event’ of December evenings occurs in the southwest at dusk, where you can watch Venus pull away from Jupiter.  Look southwest right as night falls for the two brightest things there except for the Moon.  The brighter one low in the southwest is Venus, which outshines everything else in the night sky.  Jupiter is the dimmer of the two, although it still outshines all the stars we ever see at night.  Venus and Jupiter begin the month about 2 degrees apart (your finger at arms length blocks about 1 degree.)  However, Venus will extend that gap quite noticeably each night, until it appears high above Jupiter on December 31. 

Mercury emerges from the Sun’s glare in time to form a nice pair with Jupiter on New Year’s Eve.  As you prepare to ring in 2009, take a moment to look at Mercury just to Jupiter’s left in late twilight.  That same night, the Moon will be near Venus. Saturn can be found high in the south at dawn.  Mars is lost in the Sun’s glare this month, and will remain out of sight into 2009.  It is directly behind the Sun (in conjunction with the Sun) on December 5.

Orion no céu
Creative Commons License photo credit: giumaiolini

The enormous Summer Triangle, consisting of the stars Deneb, Vega, and Altair, sets in the west.  The Great Square of Pegasus is overhead at dusk.  The star in its upper left hand corner is also the head of Andromeda.  Facing north, you’ll see five stars in a distinct ‘M’ like shape—this is Cassiopeia, the Queen.  Her stars are about as bright as those in the Big Dipper, and she is directly across the North Star from the Dipper.  In fall and early winter, while the Dipper is low and out of sight, Cassiopeia rides high.

Dazzling Orion rises in the east, reminding us that winter is on the way.  His belt points up to Aldebaran, the eye of Taurus the Bull.  By 9 pm tonight (7 pm by New Year’s Eve), the Dog Stars Sirius and Procyon will have risen below Orion in the east.  Sirius is the brightest star we ever see at night. 

Moon Phases in December 2008:

1st Quarter         December 5, 3:25 pm
Full                     December 12, 10:38 am
Last Quarter        December 19, 4:30 am
New                    December 27, 6:22 am

At 6:04 am on Sunday, December 21, the Sun is directly overhead at the Tropic of Capricorn, meaning that the North Pole is tilted as much as possible away from the Sun.  This is the winter solstice.  For people in the Northern Hemisphere, December 21 has less daylight and more night than any other day of the year. 

Sunset at Appalachian Trail
Creative Commons License photo credit: Pardesi*

However, the earliest sunsets occur on December 1 and 2.  We are already close enough to the solstice that the Sun’s apparent path across the sky on December 21 is only slightly lower than on any other day this month.  Meanwhile, Earth is about to make its nearest approach to the Sun, called perihelion, in January.  As a result, the Earth is speeding up.  The effect isn’t much (Earth’s orbit is nearly circular), but it’s enough to make both sunrise and sunset a little later each day this month and next.  With the Sun’s apparent height in the sky not changing that much in December and January, the small effect of Earth’s acceleration near perihelion dominates.  Since most of us sleep through sunrise and witness sunset, the days seem be slightly lengthening between the beginning of the month and the 21st, although they are actually getting slightly shorter.