April 2005 Skies

April is the first full month of Spring.  It brings us much warmer weather and significantly longer days than nights!

Although we can still view the rich stars and constellations of Winter by observing in the EARLY evening, most of these objects will be setting between 9:30 and 11 p.m.  They will continue to set earlier each day until most are gone by May.  April is also a very convenient month to view Spring constellations and stars.  A few northerly stars of early summer will start to become visible by late April.

For persons in Arizona, there will also be a VERY small Partial Eclipse of the Sun on April 8th!

The Sun begins April in the Zodiac constellation of PISCES, where it remains until April 18th, when it enters ARIES.

The Evening Sky
Early April sunsets occurs at about 6:45p.m., while end of month sunset occurs at 7:04p.m.  Since morning sunrises are also occurring earlier each day, April is Arizona’s first full month for the days to be longer than our nights.

The first 3rd QUARTER MOON of April is found on the 1st of the month in the Zodiac constellation of SAGITTARIUS.  April’s NEW MOON occurs the early afternoon of April 8th in the PISCES.  The 1st QUARTER MOON is found on April 15th in GEMINI high in the South at sunset.  The FULL MOON rises just before sunset on the evening of the 23rd in the Zodiac constellation of VIRGO.  Finally, April’s second 3rd QUARTER MOON closes out April the afternoon of the 30th in CAPRICORNUS.

The new crescent Moon first appears low in the West after sunset on April 9th.

The Moon will be seen near three planets and four times near prominent stars during April:

Moon & Planets:
MARS on the mornings of April 3rd & 4th,
SATURN on the evening of the 15th, and
JUPITER overnight the 21st- 22nd

Moon & Prominent Stars:
Crescent Moon near the Pleiades star cluster in TAURUS the evening of the 11th
1st Quarter Moon near bright Castor & Pollux in GEMINI on the 15th
Waxing Moon near bright Regulus in LEO overnight on the 18th
Full Moon near Spica in VIRGO overnight on the 23rd
Third Quarter Moon near Antares in SCORPIO on the morning of the 27th.

Evening Planets:  MERCURY has now returned to the morning sky. VENUS, once again an Evening Planet, remains very near the Sun all month.  However, SATURN, JUPITER and MARS can be observed in April.

SATURN rises at Noon on April 1st in the Zodiac constellation of GEMINI and is high overhead at sunset.  By month end, Saturn still appears high in the West after sunset and sets at about Midnight.  Saturn’s rings, tilted away from the Earth, make a fine sight in even small telescopes, which should also show Saturn’s largest satellite Titan orbiting outside the rings.

Recall that Earth’s “Huyghens” space probe made a soft landing on Titan’s surface in January.  Huyghens discovered weathered terrain, an atmosphere of methane and nitrogen, and icy water rocks lying nearby on the surface.  See the link below to visit the European Space Agency’s website for Huyghens and Cassini [the “mothership”].  Many photographs of Saturn and its moons are posted there to view and download!

Jupiter stands at Opposition in Virgo on April 2nd, exactly opposite the Sun in the sky (just like a Full Moon). That night it rises at sunset and remains visible all night.  Jupiter rules as the brightest object in the sky after the Moon.  A good pair of binoculars should show Jupiter’s four brightest satellites: Io, Europa, Ganymede, and Callisto near the planet’s equator.  Because each satellite alternately moves in front of the planet and is later eclipsed by Jupiter, each evening presents a different pattern of one to all four of these “stars” moving back and forth along the equatorial plane of Jupiter.  Viewers with a small telescope should also observe Jupiter’s prominent cloud bands along both sides of the planet’s equator.

What Else to See? 
A Weak Solar Eclipse but Spectacular Constellations

On April 8th in mid-afternoon there will be a solar eclipse.  It will be Total for equatorial regions in the Pacific Ocean and Western Caribbean, including Panama.  Elsewhere in the Western Hemisphere, a Partial Eclipse is seen north and south of the Total Eclipse line.  However, Arizona is so far away from the totality region that we will only see the Moon barely nick the edge of the Sun.  So, expect no roosting birds or dimming sunlight!  But between about 2:35 p.m. and 3:20 p.m. a few percent of the Sun will be covered.

CAUTION:  NEVER LOOK DIRECTLY AT THE SUN!!

Homemade filters – Including Welder’s Glasses – are NOT SAFE to use!!  A safe way to view the partially eclipsed Sun is with professional equipment OR by projecting the Sun’s image onto a card held a safe distance behind a telescope or binoculars.  Alternatively, a pinhole in a card held high overhead will show the Sun’s round image on the ground.  A small “nick” in the Sun’s Southern edge will be visible between the times given above.

Yes! When a solar eclipse occurs, there should also be a lunar eclipse 2 weeks earlier or later! However, 2 weeks earlier than April 8th the Moon missed the Earth’s shadow (no eclipse) and on the morning of April 24th, there will only be a Penumbral (outer shadow) lunar eclipse.  Most people cannot notice any difference about the Moon when it enters Earth’s extremely faint outer shadow, so we’d best wait for the next lunar eclipse, a very small but noticeable partial eclipse, which will occur in October!

Still, on early April evenings Orion will be high in the South.  On the 1st, it remains above the horizon until nearly 10:30p.m, but sets at 8:30p.m. on the 30th.  Best to gaze along the Winter Milky Way with binoculars or a telescope early in the month on dark evenings while the Moon is not visible to say a final “goodbye” to our spectacular Winter sky sights! 

LEO the Zodiac lion marks the return of Spring.  This constellation stands well above the Eastern horizon at sunset on the 1st and rises higher each April evening.  Also notice Ursa Major (the familiar “Big Dipper”) easily visible in the Northeast standing upright on the Dipper’s ladle end.  Follow the curve of the Big Dipper’s handle around to the East to see the bright orange giant star Arcturus in the constellation of Bootes the Shepherd.  Continue this curve farther along to the Southeast to find bright Spica in Virgo, and nearby the bright planet Jupiter.

The Morning Sky
The Sun rises at 6:20a.m. on April 1st as we approach the beginning of Spring.  On the 31st, sunrise is more than a half-hour earlier, at 5:42a.m.

The waning MOON is seen in morning April skies before the New Moon on April 8th and again after Full Moon on the 23rd through the end of the month.

On the morning of April 3rd the crescent Moon eclipses the red supergiant star Antares in SCORPIO.  This bright star disappears behind the Moon’s bright Eastern edge at about 3:00 a.m. and reappears at the Moon’s dark Western edge shortly after 4:00a.m.  Don’t miss this rare occurrence, so begin viewing no later than 2:45a.m. and observe the Moon’s relentless motion!  The Moon moves ever Eastward at a rate of approximately its own diameter per hour, so it rather quickly approaches and eclipses Antares.  The star’s reappearance is even more spectacular on the Moon’s dark side, with Antares suddenly reappearing in the scorpion’s heart! 

At almost the same time Antares reemerges from behind the Moon, another fainter star, HR6145, is occulted in exactly the same manner.

Morning Planets: 
MERCURY and MARS

MERCURY is difficult to observe during April.  Its path in the sky makes a shallow angle with the horizon during April, so it is never far from the horizon even by sunrise.  Between April 20th and the end of the month, it might be glimpsed by sharp eyed observers with binoculars very low in the East at about 5:00a.m.  Sweep low near the Eastern horizon and Mercury may be seen for just a few minutes before fading into the dawn.

MARS begins April in the Zodiac constellation of CAPRICORNUS, rising at about 3:30a.m.  The red planet also remains fairly near the Sun all month while moving into AQUARIUS on April 27th.  On the 30th, Mars rises at 2:41a.m., only 3 hours before sunrise and stands less than 20 degrees above the horizon when twilight begins.

What Else to See?  
The Moon will be visible near the Milky Way twice in April.  Observers with binoculars or small telescopes may watch it occult (eclipse) or approach very close to stars of 6th magnitude or brighter.  Look on the mornings of April 3rd (Antares and HR6145), April 25th, 26th, and 29th. Also watch on the evenings of April 14th, 15th, 15th, 16th, 18th, 21st, and 25th, 30th and 31st.  A listing with specific times for these events can found here.

On Friday, April 8th beginning at about 6:00p.m., the East Valley Astronomy Club will be hosting a Free Public Star Party at their observatory site East of the Gilbert Public Library.  Several telescopes will be available for public viewing of the many interesting springtime astronomical objects.

Good Luck Observing!