May 2005 Skies

May: the second full month of Spring.  May is the last month of the year in which the sun rises earlier each morning and sets later each evening.  Next month, June brings us the season of Summer and, after June 21st, progressively shorter days once again.

April was the last month to conveniently observe Winter stars and constellations.  However, in early May we may still be able to glimpse some of the most northerly Winter objects shortly after sunset.  May is also the first month we start to conveniently view Summertime constellations and stars.

The Sun begins May in the Zodiac constellation of ARIES the Ram, where it remains until May 14th, when it enters TAURUS the Bull.

May’s NEW MOON occurs early on the morning of May 8th in ARIES.  The 1st QUARTER MOON occurs on May 15th in LEO high in the South at sunset.  The FULL MOON is on May 23rd.  On that night, moonrise will be shortly after sunset and you should notice the Moon lying close to the red star Antares in the Zodiac constellation of SCORPIO.  Finally, the Moon reaches 3rd QUARTER phase late on the 29th in AQUARIUS.

The Evening Sky
Early May sunsets occur at about 7:05p.m., while sunset on the 31st is at 7:26p.m.  Since morning sunrises are also occurring earlier each day, the duration of daylight progressively increases during May from 13hours, 43 minutes on May 1st to 14 hours, 5 minutes on May 31.

The Moon:
The evening Moon will be seen near three planets during May: 
VENUS on the evening of the 9th.
SATURN on the evenings of the 12th and 13th
JUPITER overnight on the 19th.
Third Quarter Moon near Antares in SCORPIO on the morning of the 27th.

The 1 ½ day old baby Crescent Moon should be easily visible after sunset on May 9th.  Look shortly after sunset that evening for the Moon, VENUS and the red star Aldebaran in Taurus to form an equal-sided triangle in the sky.  Use binoculars to find Venus very low in the sky and directly below the Moon about 20 degrees NORTH of West.  Aldebaran will then be found closer to the Horizon and to the left of the Moon.

During the daytime on May 19th, the Moon will eclipse Jupiter, but this event is only visible for observers located approximately between Northern Mexico and Lima, Peru.

Moon & Prominent Stars:
Waxing Moon near Castor & Pollux in GEMINI on the 12th  and 13th.
1st Quarter Moon near Regulus in LEO overnight on the 15th and 16th.
Nearly Full Moon near Spica in VIRGO overnight on the 20th.
Recently Full Moon occults (eclipses) Antares in Scorpio overnight May 23 – 24.

At about midnight on the night of May 23 – 24, the Full Moon will eclipse the red supergiant star Antares in SCORPIO.  This bright star disappears behind the Moon’s Eastern edge at about 11:50p.m. on the 23rd and reappears at the Moon’s Western edge shortly after 1:10a.m. on the 24th.  Don’t miss this unusual occurrence, so begin viewing earlier in the evening to watch the Moon slowly approach Antares.  A few minutes after Antares emerges from behind the Moon, a fainter star (HR6145) will also be eclipsed by the Moon, reappearing about 2:20a.m.

Evening Planets.  VENUS, SATURN and JUPITER.  VENUS remains near the Sun all month, and will be most easily visible late in the month.  However, binoculars should show bright Venus very low in the Western sunset glare all month.  On May 8th the ½ day old crescent Moon passes Venus and they might be visible to observers with binoculars and a clear view down to the Western horizon. Look for the Moon 3 degrees (6 Moon widths) to the right of Venus about 25 to 30 minutes after sunset.

SATURN and JUPITER can be observed all month, since they are May’s brightest dark sky objects (after the Moon). 

SATURN stands in GEMINI all month and is seen high overhead in the South and West after sunset.  By month end, Saturn sets at about Midnight, so is plenty of time to observe it with a small telescope or at a Public Star Party (see below).  Saturn’s rings, tilted away from the Earth, make a fine sight in even small telescopes, and Saturn’s largest satellite, Titan, should be visible orbiting outside the rings.

JUPITER is in VIRGO all month and visible almost all night.  It sets near dawn on May 1st but  sets earlier — about 2:30a.m. — at month end. A good pair of binoculars will show Jupiter’s four brightest satellites: Io, Europa, Ganymede, and Callisto.  These are also known as the “Galilean” satellites in honor of their discoverer, Galileo.  Since Jupiter is not significantly tilted, its equatorial regions with distinct cloud bands and the famous Great Red Spot are visible each night.  The newsstand magazines “Sky and Telescope” and “Astronomy” contain diagrams showing where the satellites are located each evening for easy identification.

What Else to See?
Winter’s prominent constellations of Orion, Canis Major, Canis Minor and Auriga are no longer visible in May. Even Leo the lion appears in the Western sky in May.  However, mid-Spring brings us excellent views of the Spring and early summer constellations of: Virgo, Corvus, Bootes, and Hercules in the Eastern sky at dusk.  Ursa Major (the familiar “Big Dipper”) now stands high above the North Star Polaris in May.

After about 9:30p.m. look low in the East and Northeast for Summer constellations Vega, Cygnus, and Aquila.  Their brightest stars (Vega, Deneb, and Altair) make up the “Summer Triangle” of bright summertime stars. Also look low in the Southeast for Scorpio to be rising, led by the scorpion’s three “head” stars and a bit below, the bright red supergiant star Antares.

Before midnight, these will all be seen high in the eastern sky signaling the approach of summer.

The Morning Sky
The Sun rises at 5:42 on May 1st.  On the 31st, sunrise is more than a half-hour earlier, at 5:21a.m.

The waning MOON appears in morning May skies through the 7th and again from about the 20th through the end of the month.  The morning Moon is seen near: 

MARS on the morning of May 2nd.
MERCURY on the morning of the 6th.
The 3rd Quarter Moon stands near Antares in SCORPIO on the morning of the 27th.

Morning Planets:  MERCURY and MARS.
MERCURY is very difficult to observe during May.  Though near Greatest Western Elongation on the 1st, it is never visible in a dark sky.  Rising barely an hour before sunrise on the 1st, it might be observed briefly with binoculars in the brightening dawn low near the Eastern horizon until mid-month.  After midmonth, it will be lost in the bright dawn as it heads rapidly back toward the Sun.

MARS remains in CAPRICORNUS all month.  Rising at about 2:35a.m. on the 1st, it is first seen an hour earlier on the 31st.  Mars can now be conveniently observed in a dark sky, but even a fairly large telescope will still show a very small disk, because Mars is actually on the far side of the Sun from the Earth.

What Else to See?   The Moon will be visible near the Milky Way twice in May.  Observers with binoculars or small telescopes can watch it either eclipse or approach very close to stars of 6th magnitude or brighter on the mornings of May 21st, 23-24 (Antares), 28th, and 29th.

Also watch on the evening of May 23rd as Sigma Scorpii, a 3rd magnitude naked eye star is eclipsed by the Moon.  Specific times for these events are given here.

On Friday, May 13h beginning at about 6:30p.m., the East Valley Astronomy Club will host a Free Public Star Party.  It is at their observatory site due East of the Southeast Regional Public Library in Gilbert (Southeast of the intersection of Greenfield and Guadalupe Roads).  Several telescopes will be available for public viewing of the many interesting springtime astronomical objects.

Good Luck Observing!