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Explanation: Sweeping north in planet Earth's sky, Comet Lovejoy's greenish coma and blue tinted ion tail stretched across this field of stars in the constellation Taurus on January 13. The inset at the upper left shows the 1/2 degree angular size of the full moon for scale. So Lovejoy's coma appears only a little smaller (but much fainter) than a full moon on the sky, and its tail is visible for over 4 degrees across the frame. That corresponds to over 5 million kilometers at the comet's estimated distance of 75 million kilometers from Earth. Blown by the solar wind,...

Explanation: Blasting skyward an Atlas V rocket carrying a U.S. Navy satellite pierces a cloud bank in this starry night scene captured on January 20. On its way to orbit from Space Launch Complex 41, Cape Canaveral Air Force Station, planet Earth, the rocket streaks past brightest star Sirius, as seen from a dark beach at Canaveral National Seashore. Above the alpha star of Canis Major, Orion the Hunter strikes a pose familiar to northern winter skygazers. Above Orion is the V-shaped Hyades star cluster, head of Taurus the Bull, and farther still above Taurus it's easy to spot the...

Explanation: What causes the structure in Comet Lovejoy's tail? Comet C/2014 Q2 (Lovejoy), which is currently at naked-eye brightness and near its brightest, has been showing an exquisitely detailed ion tail. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure. Following...

Explanation: Heading north, Comet Lovejoy (C/2014 Q2) is putting on its best show for comet watchers now, with moonlight absent from mid-January's early evening skies. An easy binocular target and just visible to the unaided eye from dark sites, the comet sweeps across the constellation Taurus the Bull in this deep night skyscape. The starry scene was captured just two days ago on January 12, from Jackson Hole, Wyoming, planet Earth. In fact, the head of Taurus formed by the V-shaped Hyades star cluster points toward Lovejoy at the right. The comet's greenish coma and tail streaming in the anti-sunward...