SOHO Comets

Overview of the Solar and Heliospheric Observatory (SOHO)

Since its launch in 1996, a satellite called Solar and Heliospheric Observatory (SOHO) has taken the understanding of comets orbiting near the Sun, to another level.  SOHO can expose stars, or comets, which are extremely close to the Sun by using a coronagraph.  A coronagraph is a solid disk attached to the telescope, which blocks direct sunlight.  The disk acts like an artificial eclipse. 

 

As of January 3, 2013, SOHO has discovered or rediscovered over 2,430 comets orbiting close to the Sun, which is more than half of all known comets ever discovered.  To be accurate, people with an internet connection have discovered or rediscovered the majority of these 2,430 comets. SOHO simply captures images. It cannot analyze them. SOHO's images are left to the general public, who can look through them online once every half an hour attempting to find a comet—even though their precious find might have its life claimed by the Sun.

 

In the early days of its launch, astronomers consumed by other work at the U.S. Naval Research Lab and NASA Goddard Space Flight Center would quickly look at the images from SOHO and identify only the brightest comets as they approached the Sun.  Battams says, “Around 1999 or 2000, word got out among amateur astronomers that SOHO was posting images online and that’s when the discovery of comets, even faint ones, exploded.” Over the years, SOHO has captured many comet including Comet Lovejoy (C/2011 W3) and Comet McNaught (C/2006 P1). In December of 2013, SOHO captured Comet ISON (C/2012 S1), a comet that had a chance to become one of the brightest comets in recorded history.

 

If you wish to join the ranks of comet hunters, you can do so on this NASA website, which includes still images from SOHO and animated movies you can view. Don't expect Toy Story 3. NASA is simply creating GIF or MPEG "movies", by holding a still image for four frames before moving on the next still image. In other words there are 7.5 still frames per second. Stringing together a movie of still images allows comet-hunters, to see the movement of comets much easier.

 

Comets with perihelion this close to the Sun have been among the brightest comets in history.