Sky Roundup: January, 2009

New Year, New Sky

As the new year dawns, so, too, does the Sun rise across a land largely locked in cold around the Northern Hemisphere. After all, this is Winter across the Great Lakes where both ice and snow are the usual seasonal regimen. As bleak as it may appear outside, we resolve to be warmed inside as this month heralds a new beginning for the year upon us, a chance to start afresh, hence the annual ritual of making New Year’s resolutions.

Most resolutions seem to center around changes to our behavior about which we may feel remiss. So, for example, we intend to lose a few pounds or do more exercise. Do astronomers make any resolutions? Perhaps some decide to take out their telescopes more often, even when low temperatures in Winter or hungry mosquitoes in Summer are both biting. Others may plan to broaden their traditional range of observing and try new techniques, such as attempting a Messier marathon or making an investment in digital imaging.

We at the Cleveland Museum of Natural History resolve to do all of the above. We need to shed a few pounds of older telescopes from our inventory; we need to exercise our better telescopes and deploy them more often near our rooftop observatory; we expect to try a Messier marathon before the season of Spring; and, we’ll continue to advance our techniques in digital imaging.

All of these resolutions are coincident with the designation of 2009 as the International Year of Astronomy. A program with a stellar list of partners, several of whom include NASA (i.e., the National Aeronautics and Space Administration), the National Science Foundation, the Astronomical Society of the Pacific, and the Astronomical League, the International Year of Astronomy marks the 400th anniversary of Galileo’s historical first use of the telescope and the publication of Johannes Kepler’s Astronomia Nova (viz., The New Astronomy). Further, the celebration of the International Year of Astronomy offers institutions like schools, libraries, museums, and planetariums a suitable vehicle to host activities connected with the astronomical use of the telescope.

We astronomers at The Cleveland Museum of Natural History will feature an event or highlight an activity every month in 2009 to draw attention to the International Year of Astronomy. We expect to host a Messier marathon, new sky shows, telescope-making classes, star parties, lectures, and workshops for the visiting public and for students and teachers. Look to the CMNH website and Sky Roundup for details throughout the year about IYA.

IYA: The International Year of Astronomy in 2009 marks the celebration of 400 years of the telescope as an instrument of science and discovery.

In the meantime, January skies hold promise for some serious Winter observing. The largest planet, Jupiter, and the smallest, Mercury, meet for a couple days, from New Year’s Eve onward, low in the southwest during evening twilight (between 5:00 and 6:00 p.m. for Clevelanders). See chart 1. A good binocular should spot them just above a clear horizon. The two part company in the ensuing days as Mercury reaches greatest elongation on January 4, that is, its greatest angle east of the Sun as seen from Earth, while Jupiter sinks out of sight. Brilliant Venus continues to climb higher in the sky and dominates the early evening hours. By mid-month, Venus reaches its own greatest elongation, while Mercury, like Jupiter previously, drops below the horizon.

Star Chart 1: Mercury and Jupiter meet in the southwest sky early in the month just after sundown. Look for them in evening twilight.

Saturn resolves to make its presence known in the wee hours of January, shining pale yellow below the tail of Leo (the Lion) marked by the nearby star Denebola. See chart 2. A glance through a telescope at its famous rings shows them less conspicuous, as later this year the Earth will pass through the plane of Saturn’s rings, a phenomenon that occurs about every 15 years. By September, 2009, the relatively thin rings will seem to disappear from view in a small telescope. Only a large telescope will resolve the thin rings edge-on; so, a rare sight of ringless Saturn will be the real treat for observers.

Star Chart 2: Saturn shines alone in pre-dawn skies below the constellation of Leo (the Lion) near the star Denebola, the tail of the Lion. A good telescope shows the pale planet’s diminishing rings.

The Moon this month also resolves to get some attention in our New Year’s sky, gliding ever so close to the Pleiades (aka M45) on January 7; unfortunately, that close passage occurs during daylight hours for us in Cleveland. So, either night before or after that date, one will catch the waxing gibbous Moon fore and aft the Seven Sisters. However, the Moon does glide south the Beehive Cluster (aka M44), a quaint smattering of stars in Cancer (the Crab), on January 12, which will be visible in pre-dawn hours to us Clevelanders. See chart 3. Also, the Moon initiates a rare spectacle of Nature, namely, an annular solar eclipse, the resolution of which is only visible from southern Africa, Australia, Southeast Asia, and Indonesia.

Star Chart 3: The waning gibbous Moon shines bright in the vicinity of the Beehive Cluster in the early hours before dawn on January 12.

Total eclipses occur when the Moon (at New Moon phase) covers the disk of the Sun as seen from Earth. Annular eclipses are rarer and occur when the Moon does not fully cover the disk of the Sun; consequently, at the eclipse’s midpoint, the bright Sun appears as a ring (or annulus) of light around the dark silhouette of the Moon. In this instance, the Moon does not appear to cover the Sun completely when an eclipse coincides with the Moon’s apogee, or its farthest distance from Earth. This coincidence does occur this January for observers on the other side of the world, hence the annulus of sunlight.

The month’s Full Moon also resolves to achieve a high-water mark for itself as Earth’s nearest celestial neighbor influences our coastal waters in a very real sense. On January 10, the date of the phase of the Full Moon is very close to that instance when the Moon normally approaches closest to Earth. Perigee is the term for the Moon’s monthly closest approach to Earth. In January, perigee coincides with the Full Moon phase, so the Moon’s gravitational influence on the tidal waters of Earth becomes greatest. If you live near a coastal area, resolve to face higher-than-usual tides. Those of us living near the shoreline of Lake Erie, though, do not have to worry about high tides since the Great Lakes do not exhibit this phenomenon to any great extent.

There’ll be more news on the International Year of Astronomy and our resolutions for 2009 in later installments of Sky Roundup. Happy New Year and a fresh, clear, new sky to all!

Sky Roundup Almanac for Cleveland, January, 2009

January 1: Jupiter and Mercury just over 1º apart, seen in southwest sky
January 2: Algol at minimum
January 4: First Quarter Moon; Mercury at greatest elongation, seen in southwest sky
January 5: Algol at minimum
January 9: Algol at minimum
January 10: Full Moon (largest in 2009) and nearly at perigee (hence, large tides)
January 11: Algol at minimum
January 13: Algol at minimum
January 14: Venus at greatest elongation, i.e., greatest angular distance east of Sun, 
                   seen brilliant in evening sky after sunset
January 15: Saturn north of waning gibbous Moon, seen in morning sky before sunrise
January 16: Algol at minimum
January 17: Last Quarter Moon
January 19: Algol at minimum
January 22: Algol at minimum
January 25: Algol at minimum
January 26: New Moon
January 28: Algol at minimum
January 30: Venus south of waxing crescent Moon
January 31: Algol at minimum

Questions or comments?
Please contact: Jason Davis at 216-231-4600, x3519, or jdavis@cmnh.org