Bright Comet observed by SOHO while the Sun ejects Earth directed CMEs

Status Report From: Goddard Space Flight Center
Posted: Wednesday, October 24, 2001

A very bright Sun-grazing comet was discovered by SOHO while a pair of coronal mass ejections are heading for Earth following two explosions above sunspot 9672 on Monday, Oct. 22nd. The expanding cloud(s) will likely strike our planet's magnetosphere on Oct. 24th or 25th and trigger a new round of geomagnetic activity.

A Sun-grazing comets was spotted in the LASCO C3 field and can be seen moving towards the Sun from lower right while the Earth directed CME blast out from the Sun as seen in this mpeg animation:

The comets tail grows as it approaches the Sun and a long tail can be seen in the images and animation from the LASCO C2 field of view. This is one of the brightest comets observed by SOHO:

Here is one still image of the comet. In all these images the shaded disk is a mask in the instrument that blots out direct sunlight. The white circle added within the disk shows the size and position of the visible Sun.

SOHO has discovered more than 365 comets in just under 6 years which makes SOHO the most prolific comet finder in the history of astronomy.

Solar radiation heats the comet which in turn causes the outgassing of the water molecules and dust. The dust scatters sunlight at visible wavelengths, making the comet bright in LASCO images. The water molecules break down into oxygen and hydrogen atoms, and the hydrogen atoms interact with the coronal plasma.


Launched almost 6 years ago as a project of international cooperation between the European Space Agency and NASA, the Solar and Heliospheric Observatory has revolutionized the science of the Sun.

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