Credit: SOHO (NASA & ESA)

NASA recently published an exquisite image of the Sun, acquired by the Sun-orbiting Solar and Heliospheric Observatory (SOHO) spacecraft. During the period 19-21 October 2010, SOHO monitored a comet that appeared to be falling  toward the Sun. Sun’s heat and pressure must have destroyed the comet, a small flimsy object, composed of ice and cosmic dust. Interestingly, the image also shows the planet Mercury, the smallest and innermost planet.

The image was acquired by an instrument aboard SOHO, termed the coronagraph. The SOHO coronagraph occults the Sun by an opaque disc, to produce an artificial solar eclipse, enabling scientists to study, in detail, the dynamic outer solar atmosphere, which is immersed in intense sunlight. The Sun-grazing comet was discovered by Bo Zhou, a Chinese comet hunter, on 19 October 2010, in the SOHO coronagraph images. Comet hunters are astronomers who specialize in discovering and observing comets.

In these images the blocked Sun is represented by a white circle. SOHO is regarded as the most successful comet discoverer in history, since it has spotted over 1,900 comets. Intriguingly, there is currently a public contest to guess when the number of SOHO’s comets will hit 2,000.

The comet is likely a member of a peculiar category of comets, known as the Kreutz sungrazers family. This group of comets is named after Heinrich Kreutz (1854-1907), the German astronomer who studied them in detail. The Kreutz sungrazers are believed to be fragments from a shattered giant comet. It is estimated that several of these comets venture into the Sun, and disintegrate, every day. However, most are too small to detect, but occasionally a big fragment blazes in the Sun’s tenuous, extremely hot atmosphere.

SOHO is a joint project between NASA and the European Space Agency (ESA). It was launched into space on 2 December 1995, to be placed into a special orbit around the Sun, located about 1.5 million km from Earth’s orbit. SOHO has acquired numerous images and made startling discoveries that revolutionized astronomers’ understanding of the Sun. It is regarded as one of the greatest and most successful scientific projects.

References

SOHO Press Release

http://sohowww.nascom.nasa.gov/pickoftheweek/

Wikipedia

Further Reading

http://sohowww.nascom.nasa.gov/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist