What are the white streaks I can see on the images? Are they comets?
No, the white streaks are caused by tiny particles (cosmic rays) hitting the camera. Some examples of cosmic rays can be seen in this image. • Why aren’t the images up-to-date? What is a ‘keyhole period’? We are often not in continuous contact with SOHO, so you will often see that the images have not been updated for some time. The schedule of spacecraft contact can be found here. Every few months, we go into a ‘keyhole’ period, in which we have very limited contact with SOHO. It is during this time that SOHO performs its roll manouver — this is necessary to keep SOHO’s high-gain antenna pointed towards Earth. See this page for more details on the keyhole and SOHO’s roll. Back to Top Sungrazing Comets: • What is the definition of a sungrazing comet? There is no definition of a sungrazing comet. All of the comets discovered by SOHO pass close to the Sun, and could be regarded as “sungrazers”, but the Kreutz group of comets are the definitive sungrazers. They get as close as 50,000Km fr
