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Grab a Comet by the Tail

Lovejoy awaits at the edge of sight

Lovejoy awaits at the edge of sight

The waning gibbous moon rises around 8pm Thursday, with Jupiter high above it. Between them is the blue-white star Regulus of Leo the lion. Sunday the moon rises around 11pm, with the white star Spica 10 degrees beneath it. As daybreak approaches Monday morning, the two are even closer together high in the southwest. That evening the moon rises just before midnight, and now it is the one trailing Spica. Before dawn Thursday the 12th, the now-crescent moon shines within 10 degrees of golden Saturn, with Antares, the red heart of Scorpius, a little farther toward the horizon.
    The waning moon leaves the evening sky bereft of its powerful glow, making these next two weeks your best chance to spot  Comet Lovejoy before it’s gone forever — or at least the next eight thousand years. The fifth magnitude comet hovers at the border of naked-eye visibility between the constellations Perseus and Andromeda.
    Binoculars will bring it into view as a faint, oblong smudge, while even a modest telescope will reveal its brighter coma and trailing tail. You might even be able to discern the green-glowing head of the comet and its blue-hued tail. These colors are a tell-tale sign of the comet’s molecular composition, the green from diatomic carbon and the blue from carbon monoxide, both being charged by interstellar ultraviolet radiation. In contrast, naked-eye comets appear white, a result of sunlight reflecting off particles of dust and debris.
    Technically titled C/2014 Q2, the comet is named after amateur astronomer Terry Lovejoy, of Australia, who discovered it last August. Lovejoy has identified four earlier comets.
    Night by night, Comet Lovejoy is inching north, from the feet of Andromeda toward the outstretched arm of Perseus. By this time next month it will be one, if not two, magnitudes dimmer and much harder to find as it heads to the outer solar system.
    Closer to home, Venus and Mars hover above the west-southwest horizon at twilight on their way to a fabulous conjunction later this month. They are maybe a half-dozen degrees apart this weekend, the size of your fist held at arm’s length. And Jupiter shines from sunset to sunrise.