Follow Comet C/2002 V1 (NEAT) with SOHO
12 February 2003Only the most dedicated of sky watchers will have seen the latest comet, called C/2002 V1 (NEAT). It has hovered near the limits of naked-eye visibility in the evening sky since January 2003. However, you would need a pair of binoculars, pointed in exactly the right direction, to see anything. Log onto the Internet instead, and let the ESA/NASA space probe SOHO show you more about this comet than you would usually see.
The Solar and Heliospheric Observatory (SOHO) is an ESA/NASA space probe to study the Sun. One of its instruments is the Large Angle and Spectrometric Coronagraph (LASCO) that blots out the disc of the Sun, creating an artificial total eclipse. LASCO is a spectacular comet-observing tool because of its combination of high sensitivity and large field of view.
The Sun's large gravitational field provides the central force for comet orbits. Comets themselves are icy messengers, often from the outer Solar System that fall through the inner solar system, before heading back into the celestial reaches. On the way, they provide observers on Earth and in space with fleeting opportunities to catch a glimpse. Astronomers discover comets all the time. If first seen by individual observers, they are named after the discoverer. Nowadays, more and more comets are first seen by automated telescope patrols, designed to scan the skies looking for objects that could pass close to Earth. These discoveries are given catalogue references, as is the case for Comet C/2002 V1.
The last comet to pass through the SOHO field of view made its journey during the last week of January 2003. Now, armchair observers all around the world have a chance to view another comet, C/2002 V1. This time, the show may be more spectacular because C/2002 V1 (NEAT) will pass very closely by the Sun.
The comet was discovered by NASA's Near Earth Asteroid Tracking programme (NEAT). At that time, it was 25 000 times fainter than the human eye can perceive. Initially, the comet became so bright that astronomers wondered whether they would be able to see it during the day, as it rounded the Sun.
During January 2003, the comet failed to brighten as hoped. Now, it is expected to disappear from view to Earth-bound observers about 11 February 2003, as it heads towards the Sun for its closest approach on 18 February 2003. It will not be lost from all sight, however, as in space, SOHO will be watching. Astronomers expect C/2002 V1 (NEAT) to pass into LASCO instrument's field of view, early on 16 February and stay there until 20 February.
It will pass by the Sun at less than a tenth of the distance between the Earth and the Sun. There is a small chance that the Sun's gravitational field could pull it to pieces. "Even if that doesn't happen, the fly-by itself should be impressive enough," says Bernhard Fleck, SOHO Project Scientist.
Watch the comet's journey live on the Internet: http://sohowww.nascom.nasa.gov/data/realtime-images.html or http://soho.estec.esa.nl/data/realtime-images.html