A sungrazing comet called Lovejoy is near what will surely be its end. Sungrazers melted by the Sun is not really new. In fact, SOHO has become the most prolific comet observer at over 2000 and counting. But what makes this special is that it is exceptionally big, about 100 meters, and so it will be exceptionally bright as it gets closer to the Sun. It has a lot more material to melt away and so sunlight is going to really light up the comet.
Comet Lovejoy (C/2011 W3) was discovered on December 2, 2011 by Australian astronomer Terry Lovejoy. He is an early pioneer in the discovery of SOHO comets and he discovered it both with a ground based telescope and with SOHO. This is only the second Kreutz-group comet observed from the ground and the first seen both from the ground and space. This makes Terry Lovejoy the first person to observe a Kreutz comet with ground and space-based telescopes.
Kreutz comets are thought to be the remnants of a single large comet that broke up several hundred years ago. Kreutz comets are a special group of “sungrazers” because their orbits are so close to the Sun that they evaporate. They take 800+ years to orbit the Sun. Here is its orbit as it approaches within 0.2 solar radii of the Sun’s surface.
Here is a video of the comet’s path from the PROBA2 team.
Tonight (Thursday 12/15/11) at 7:30 pm ET Comet Lovejoy will reach perihelion. SDO, Hinode and Proba2 will try to observe Comet Lovejoy as it passes behind the Sun. Starting at 23:30 UTC (6:30 pm ET) the SDO spacecraft will point a little to the left of its usual position. The figure below shows the viewpoint of SDO where the circle is the edge of the Sun and the X’s are where we estimate the comet will be and the red arrow shows the direction the comet moves. From the viewpoint of SDO the comet goes behind the Sun at 00:22 UTC (7:22 pm ET).
All three instruments on SDO will be watching the comet. The EUV images from AIA would show the second comet seen in these ultraviolet wavelengths (the first was in July). HMI and AIA can use the comet to understand the roll of the spacecraft. EVE might see some of the atomic ions responsible for making the comet bright in the EUV.
STEREO/SECCHI and SOHO/LASCO have already been observing Comet Lovejoy. The hope is that SDO, Hinode and PROBA2 will also observe its demise as it is evaporated by the Sun. For SDO all three instruments will be watching the comet. AIA will take EUV images (like the first time a comet was seen in EUV in July). Both HMI and AIA will use their comet observations to understand SDOs roll. EVE will hopefully give us spectroscopic information about the composition of the comet.
We will also add more images and video here when it is available. Also, there is always The Sun Today at Facebook. Stay Tuned!
Here are a few videos, more to come!.
The first images of the comet! Faint but it is there!
Here is Lovejoy after it has come back around. Still there!
And another of it approaching the Sun.
Here is Lovejoy approaching and leaving the Sun in SOHO.