If you're a night owl, or one who tends to wake up well before sunrise, you'll have a chance to catch a lovely view of a close get-together between a bright planet and the moon early on Monday morning, Oct. 5. Check out the east-northeast sky any time after 2 a.m. local daylight time to sight a 30% illuminated waning crescent moon. And situated just to the upper right of the moon, will be a relatively bright orange yellow "star."
But that's no star but a planet. Mars.
Currently situated 152 million miles (245 million km) from Earth, Mars has been gaining prominence in the morning sky since the start of summer — albeit very slowly. In the coming days and weeks, it will become increasingly more noticeable as it draws closer to us and continues to slowly ramp up in brightness.
Beauty in the eye of the bee-holder
The pairing off of the moon and Mars will be nice, but less than a week later it will be time to break out the binoculars and telescopes, for on the morning of Oct. 10, Mars will be located near the western edge of the famous Beehive star cluster, also known as Messier 44 or M44. Then, it will be placed almost right in the middle of the cluster on Oct. 11 and finally at the cluster's eastern edge on Oct. 12.
The Beehive is one of the brightest and finest open star clusters, located in the middle of the faintest of the zodiacal constellations, Cancer the Crab. Indeed, this celestial crustacean has no star brighter than 4th magnitude and its only claims to fame are its membership in the zodiac and beautiful M44.
Dual identity
But some astronomy texts speak of this star cluster as "Praesepe, the Manger." A manger is defined as "a trough in which feed for donkeys is placed." The cluster was apparently first called Praesepe 20 centuries ago. Galileo Galilei (1564-1642) first resolved it into stars in 1610. It is easy to see through binoculars from the city and with the naked eye from a dark location. About 100 stars can be seen in good binoculars or a small telescope. The cluster's relatively "new" moniker — "Beehive" — apparently evolved almost four centuries ago, when some anonymous person, upon seeing so many stars revealed in one of the first crude telescopes, exclaimed: "It looks just like a swarm of bees!" The view through a small, low-power telescope brings out numerous stars of similar brightness ("the bees") in pairs and bunches assembled within a large, roughly elliptical area ("the hive"). Hence, the reason why some astronomy books call the cluster "Beehive," while others call it "Praesepe."
Perhaps the older designation "Praesepe" (traced back to the ancient Greeks) is preferable since in the middle of Cancer are two stars called the Aselli ("donkeys") known for over 2,000 years as Asellus Borealis and Asellus Australis — the northern and southern colts — feeding from a manger.
Coming attractions
Mars will spend the rest of the month moving toward the bluish first magnitude star Regulus, crossing from Cancer into Leo the Lion on Halloween (Oct. 31). The Red Planet brightens a bit from magnitude +1.1 to +0.9 in October and thus will appear noticeably brighter than Regulus by the time it pulls within a dozen degrees of the star at month's end.
But before it reaches Regulus, it will pass just to the north of a much brighter Jupiter on Nov. 16.
The hour before dawn, when Mars is high in the southeast, is still the best time for telescopic observation. In a telescope, though, Mars is disappointing. Currently, in most instruments it appears as nothing more than an amber-hued dot of light, not yet big enough to reveal surface features through most amateur telescopes, so don't get your hopes up. Mars will continue to approach the Earth in the weeks and months to come and will be closest on Feb. 19, when it will be 63 million miles (101 million km) away.
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope, The Old Farmer's Almanac and other publications.
