Path of COMET ISON as seen from SOHO LASCO C2 and C3 coronagraphs.

It will also be visible from the COR1 and COR2 instruments on board both STEREO spacecraft. The SOHO Hotshot webpage for Comet ISON has many more links to more details on the path of the comet as seen from SOHO and STEREO. At the moment it looks like this, as seen by the Hubble Space Telescope. It might be a spectacular sight from Earth. The appearance of comets from Earth is hard to predict because how it looks when it gets closer to the Sun depends on the details of its composition. We’ll have to wait and see!

The small, tadpole-like extended feature approximately in the center of the field of view in the image below is Comet 96P/Machholz.

Comet 96P/Machholz has an orbital period of about 5.2 years, which means it has been seen before in LASCO observations. Here is an example image from 2007

and five years before that in 2002,

The dates for the entry of Comet 96P/Machholz were obtained from the transit page of the LASCO instrument. It is projected to be visible in the LASCO C3 field of view from July 12 – 17, and it may also be visible in the images from the STEREO A/B coronagraphs.

The new movie export menu makes it easier to set the exact scaling of the area you are interested in, and the processing itself is now performed on the graphics card using OpenGL:

The SDO Cutout Service plug-in allows you to request science-quality image data from the SDO/AIA and HMI instruments for the region of interest and time range selected in JHelioviewer:

SDO/AIA will take special observations to view the comet; AIA will change its pointing and point slightly away from the center of the Sun in order to try to get more observations of the comet as it gets close to the disk of the Sun.

Why are these observations being taken? Well, we are looking for something like we saw on 2011/07/05 this year. On that day a comet fell in to the Sun. These kinds of comets have been seen before in LASCO-C3 and LASCO-C2 images. What was new about this observation was that for the first time the comet was seen against the disk of the Sun. The video below gives a description of what was seen.

SDO/AIA detects different wavelengths of light. So in order for us to see it, the comet must have been emitting at those different wavelengths, and the comet must have disintegrated in to a big enough cloud of ionized gas for us to see it. So the big scientific question about seeing this comet against the disk of the Sun is explaining both how it came to be emitting at wavelengths that SDO/AIA could see, and figuring out how it could have disintegrated. This is an active area of research, with presentations on this subject given last week at the American Geophysical Union‘s Fall Meeting, and a paper set to appear in Science.

Comet Lovejoy is already visible. YouTube and user otraLoly posted a video earlier on today of Comet Lovejoy entering the field of view of LASCO C3.

We hope you enjoy tracking Comet Lovejoy as it gets closer to the Sun. Please let us know if you have any further questions about the Helioviewer Project and Comet Lovejoy.

As the event progresses, you can clearly see that the material is spiraling around as it slowly moves away from the Sun’s surface. It may be associated with an ejection seen in LASCO C2, although the data here is as yet incomplete. Other users have also shred movies of the same event: here is one shared by danielchangck:

and another movie shared by papavalium:

If you find something interesting, please let us know by either emailing us at contact@helioviewer.org, or by sharing it on helioviewer.org via YouTube.

Thanks!

LASCO (Large Angle Spectrometric COronagraph) on board the SOHO spacecraft has seen very many comets since it started observing in 1996. SOHO has reported over 2000 comets, almost all of them found by members of the public. Thanks to the many amateur observers that hunt for comets in SOHO data, SOHO has seen many more comets than any other mission (there was another bright comet observed on May 10-11, 2011. A lot of these comets come from the Kreutz sungrazer family of comets. There is an active community of comet hunters, so if you think you’ve discovered one – and it is certainly possible that you may have – please check the latest reports over there. Thanks for sharing, galaxy387!

The STEREO (Solar TErrestrial RElations Observatory) mission is very different from the other missions (Solar Dynamics Observatory and SOHO) we feature on helioviewer.org.

First off, there are two spacecraft, called STEREO-A and STEREO-B. Both spacecraft orbit the Sun at roughly 1 AU (astronomical unit), or about as far away from Sun as the Earth is. However, STEREO-A is moving ahead of the Earth in its orbit, and STEREO-B is drifting behind the Earth in its orbit. This means that each STEREO spacecraft sees different parts of the Sun, parts that we can’t see from Earth. STEREO-B sees features on the Sun that we eventually see in SDO and SOHO, and STEREO-A allows us to see the continuing evolution of features that we did see in SDO and SOHO.

This plot shows where each spacecraft is now:

As you can see, they are quite far away from the Earth. This puts some operational constraints on each spacecraft that means we get high-quality images two days after they were taken. These are the data we are making available today; images from June 1st 2011, up to the most recently available data will be available initially. We ask for your patience, as we are uploading these images right now. Over the course of the next few weeks we will be making images from earlier in the mission available so that you can explore the Sun from many different angles over the past 4 1/2 years.

The benefit of seeing the Sun from many different angles is apparent when you look at the following three videos of the prominence eruption of June 7, 2011. The first one consists of images from SDO-AIA and SOHO-LASCO

We hope you enjoy these new images! As ever, please let us know if you spot any problems.