Skywatchers are still looking up at comet Pan-STARRS, visible in the low western horizon after sunset, but so is NASA’s solar monitoring spacecraft STEREO-B. From its cosmic perch, on the far-side of the Sun, the on-board space telescope snapped hundreds of images of the comet as it rounded the Sun from March 9th to March 16th. Now thanks to the hard work of analyst Karl Battams of the Naval Research Lab, every one of those images have been stitched together to create an awesome video of the icy interloper’s travels. (Related: Sun Erupts: Epic Blast Seen by NASA Solar Observatory)
While the Sun’s disk is off frame on the left side, the probe’s cameras have been positioned so that both the comet- complete with its magnificent tail- and even our planet Earth are clearly visible in the same shot. To add perspective Mercury is also visible on the left-side of the frame.
As the video runs and the over-exposed comet makes a bee-line up the frame, billowing Coronal Mass Ejections (CME) composed of hot plasma can be seen erupting off the surface of the Sun into space , but missing the comet entirely. If these clouds of charged particles had hit the comet, it could have caused dramatic changes to its brightness and tail structure. While unpredictable, there may be future solar eruptions in the coming days that may directly hit the comet- something astronomers are definitely keeping an eye on.
Comet-watching update: In the last week since Pan-STARRS made its closest approach to the Sun, it has slowly faded in our Earthly skies to being as bright as the stars in the Big Dipper and will continue to fade as it pulls away from the heat of the Sun and travels back to the cold , outer fringes of the solar system. (Related: Comet to Brighten Northern Skies Tonight)
Many across the Northern Hemisphere are reporting that while it remains a faint naked- eye object, binoculars and small telescopes are best to track it down in the sky glow and show off its bright nucleus and plume-like tail.
Best time to catch the comet with the unaided eye is about 30 to 40 minutes after local sunset. From my mid-northern latitude vantage point in Montreal, Canada (+45 deg. Latitude) I have been using my 15 x 70 pair of binoculars to first identify the comet in the western sky and examine the tail. It is definitely worth being patient because once the sky gets dark enough, the comet’s tail becomes more evident, currently stretching up into the sky at least 1 degree- equal to the width of two full moon disks.