UPDATE 12.19.11: Additional media added.
Caption: Comet Lovejoy as seen by the Solar Optical Telescope (SOT) on Hinode as it approached the sun early on 16 December 2011. Hinode purposely adjusted its instruments during this time period to observer the side of the sun and track the comet. Scientists were rewarded with two images, taken 30 seconds apart before Comet Lovejoy vanished into the glare of scattered light from the sun. Using these images, scientists believe the coma -- the visible cloud of ice and dust surrounding the comet -- is about 450 miles across. Since the comet is so much fainter than the sun, the SOT's original image showed a saturated, over bright sun next to the comet; this image has been processed with a replacement, less bright image of the sun that was captured simultaneously.
UPDATE 12.16.11: Additional media added.
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Comet Lovejoy survives its encounter with the sun. The comet is seen here exiting from behind the right side of the sun, after an hour of travel through its closest approach to the sun. By tracking how the comet interacts with the sun's atmosphere, the corona, and how material from the tail moves along the sun's magnetic field lines, solar scientists hope to learn more about the corona. This movie was filmed by the Solar Dynamics Observatory (SDO) in 171 Angstrom wavelength, which is typically shown in yellow.
Caption: Comet Lovejoy survived its rendezvous with the sun! This image from the Solar Heliospheric Observatory (SOHO) taken in the morning of Dec. 16, 2011 shows the comet head emerging from the right side of the sun. The comet does seem to have left its tail behind, however –that's the nearly vertical streak that remains on the left side of the sun.
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Another instrument watching for the comet was the Solar Dynamics Observatory (SDO), which adjusted its cameras in order to watch the trajectory. Not only does this help with comet research—such as how big the comet is and what it's made of -- but it may also help orient instruments on SDO. Since the scientists know where the comet is based on other spacecraft, they can finely determine the position of SDO's mirrors. This movie from SDO from the evening of Dec 15, 2011 shows Comet Lovejoy moving in toward the sun.
UPDATE 12.15.11: Additional media added.
Caption: An image of Comet Lovejoy as it moves ever closer toward the sun taken on December 15, 2011 at 4:30 AM ET. This image is what's known as a "coronograph" in which the camera -- the Large Angle and Spectrometric Coronagraph (LASCO) C3 instrument on the Solar Heliospheric Observatory (SOHO) -- obscures the sun itself so as to be able to observe its fainter atmosphere, the corona.
Caption: Comet Lovejoy blazes toward the sun and its tail wiggles as it interacts with the solar wind. By the end of the day on December 15, 2011, the comet will graze some some 75,000 miles above the sun's surface through the several million degree solar corona, and quite likely evaporate. Five different satellites -- the Solar Terrestrial Relations Observatory (STEREO), the Solar Heliospheric Observatory (SOHO), the Solar Dynamics Observatory (SDO), Hinode, and Proba -- are trying to watch its final approach to the sun. This movie was recorded by STEREO using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument.
Caption: This movie from the Solar Terrestrial Relations Observatory (STEREO) provided the first space-based views of Comet Lovejoy on December 11. The comet moves in from the bottom right. (The moving red line is an artifact caused by the planet Mercury, which is off camera.)
In 16 years of data observations, the Solar Heliophysics Observatory (SOHO) -- a joint European Space Agency and NASA mission –- made an unexpected claim for fame: the sighting of new comets at an alarming rate. SOHO has spotted over 2100 comets, most of which are from what's known as the Kreutz family, which graze the solar atmosphere where they usually evaporate completely.
But on December 2, 2011, the discovery of a new Kreutz-family comet was announced. This comet was found the old-fashioned way: from the ground. Australian astronomer Terry Lovejoy spotted the comet, making this the first time a Kreutz comet has been found through a ground-based telescope since the 1970's. The comet has been designated C/2011 W3 (Lovejoy).
Discovering a comet before it moves into view of space-based telescopes, gives scientists the opportunity to prepare the telescopes for the best possible observations. Indeed, since comet Lovejoy was visible from the ground, scientists have high hopes that this might be an exceptionally bright comet, making it all the easier to view and study. (Some Kreutz comets –- such as Ikeya-Seki in 1965 -- are so bright they can be seen with the naked eye in the daytime, though this is extremely rare.)
The comet moved into view of the Solar Terrestrial Relations Observatory (STEREO) on Monday, December 12. It should be visible in SOHO by Wednesday, Dec 14.
Next up is Hinode, which will make observations at about 6 p.m. ET on Dec 15, as the comet moves towards its closest approach to the sun. Hinode's solar optical telescope will take the highest resolution images of this close approach. As the comet passes through the sun's atmosphere, the corona, an increase in particle collisions may produce X-rays, so Hinode may also capture X-ray images of the comet.
The comet will likely pass within some 87,000 miles of the sun, and disappear behind the northwest limb of the sun shortly after it is seen by Hinode.
For additional updates please watch: http://sungrazer.nrl.navy.mil/index.php?p=news/birthday_comet