Upcoming total lunar eclipse
By Phyllis Pitluga
Total lunar eclipse, by Fred Espenak, 2000. Like our upcoming eclipse where the Moon will pass south of the center of Earth’s shadow, this photo shows the southern half of the Moon as brighter than the northern half of the Moon.
Soon we will be treated to one of nature’s awesome celestial sights—a total lunar eclipse—when the full moon disappears into darkness or may even turn a coppery red for nearly an hour. The moon will be moving eastward into Earth’s shadow and between the bright star, Regulus (above) and the planet Saturn (below). You can watch this astronomical phenomenon from anyplace where you have a clear eastern view.
Other things to observe during the eclipse are the shape of Earth’s shadow on the moon as the eclipse begins (which shows the shape of our planet), the color of the shadow at mid-eclipse (affected by the clarity of the air above the sunrise and sunset “edges” of Earth), the multitude of stars visible during totality and the moon’s eastward movement into the shadow (as the moon orbits Earth) while the whole eastern sky is rising, due to the Earth’s rotation.
The sequence for this lunar eclipse is:
6:34pm: The full moon rises.
6:36pm: The moon starts to enter the faint penumbral shadow.
6:44pm: The sun sets.
7: 43pm: The moon starts to enter the dark umbral shadow.
9:01pm: The moon completely enters the dark umbra.
9:26pm: Mid-total eclipse—what color will the moon be?
9:50pm: The Moon begins to exit the dark shadow.
11:08pm: The Moon completely exits the dark shadow.
Our Earth always casts a shadow out into space. As the Sun shines on the dayside of Earth, our planet casts its shadow, creating the night side. This shadow is so long that it extends way beyond the Moon’s orbit (but not out to Saturn and Regulus). When the Moon is full, it is “roughly” in a line: Sun-Earth-full moon. However, the Moon’s orbit is inclined by five degrees to the Sun-Earth orbit line. Usually the full moon passes just above or below Earth’s shadow. However, the Moon perfectly crosses the Sun-Earth line in two places in its orbit. If the Moon is at these crossing places when it is new moon or full moon, an eclipse will occur. These two times are called the eclipse seasons.
In 2008, the eclipse seasons are in February and August (Annular solar eclipse on February 7 in Antarctica, total lunar eclipse on February 20 visible to half the Earth (including Mexico), total solar eclipse on August 1 across Canada, Greenland and Russia, and on August 16, a partial lunar eclipse visible over Africa and the Middle East.
Many of you will remember seeing the total lunar eclipse here in San Miguel, on March 3 2007. The eclipse seasons slip back through the calendar each year in a cycle that repeats every eighteen years, eleven and one-third days. The solar eclipses occur two weeks before or after lunar eclipses because the Moon must be between the Earth and Sun for a solar eclipse, or at new moon. The lunar eclipses occur when the Moon is full, two weeks earlier or later and at the other of the two crossing points.
As you follow the sequence of events during the eclipse on the night of February 20, use this information to appreciate the cosmic choreography that was well understood and documented in codices by Mexico’s earliest inhabitants.
Phyllis Burton Pitluga is Astronomer Emerita, Adler Planetarium & Astronomy Museum, Chicago.
Sky calendar, February 2008
By following the Moon—the biggest and brightest “pointer” in the sky—during the month you can identify many planets and bright stars. On the following nights you can relocate them but without the Moon, which moves about 25 times its own diameter from one night to the next. The Moon is much closer than the planets of our Solar System and the stars are unfathomably more distant. So, when the Moon appears close to a celestial light they are truly separated by millions, billions or trillions of miles.
Feb 1, Friday: Venus is just above Jupiter in the dawn sky and the waning crescent moon is passing beneath the bright star Antares, in the constellation of Scorpious.
Feb 4, Monday: The waning crescent moon passes below Jupiter and Venus. Notice that you can see reflected earthlight shining on the nighttime part of the Moon, creating what is called “earthshine.”
Feb 6, Wednesday: New moon and annular solar eclipse in Antarctica (on the 7 where viewing is just east of the International Date Line).
Feb 13, Wednesday: First quarter moon is halfway across the sky, west-to-east, at sunset and is passing above the Pleiades Star Cluster.
Feb 16, Saturday: Waxing gibbous moon passes above Mars.
Feb 17, Saturday: Waning crescent moon passes just beneath Mercury.
Feb 20, Wednesday: Full moon and Total Lunar Eclipse (see above).
Feb 23-Mar 8: Zodiacal light visible in the west after evening twilight for the next two weeks as a glowing cone of light (coming from meteoric and cometary dust in the plane of the Solar System which forward scatters sunlight and is especially visible now when the plane of the Solar System is reaching from the horizon to overhead here in San Miguel).
Feb 24, Sunday: Saturn rises opposite the setting Sun tonight and crosses the sky all night, setting at sunrise.
Feb 25, Monday: Mercury is above Venus in the dawn sky and they remain close until late March.
Feb 28, Thursday: Last quarter moon rises about midnight and passes below the bright star Antares.