Adler Planetarium

NASA's Hubble Sees Comet ISON Intact

Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

A new NASA Hubble Space Telescope image of comet ISON taken on October 9 suggests that it is intact despite some predictions that the fragile icy nucleus might disintegrate as the Sun warms it. In this image the comet's solid nucleus is unresolved because it is so small. If the nucleus broke apart then Hubble would have likely seen evidence for multiple fragments. The comet will pass closest to the Sun on November 28.

The coma or head surrounding the comet's nucleus is also symmetric and smooth. This would probably not be the case if clusters of smaller fragments were flying along. In addition, a polar jet of dust first seen in April is no longer visible and may have turned off.

This image was assembled using two filters. The comet's coma appears cyan, a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles are pushed away from the nucleus by the pressure of sunlight. The comet was inside Mars’ orbit and 177 million miles from Earth at this time. Comet ISON is predicted to make its closest approach to Earth on December 26, at a distance of 39.9 million miles. Comets are mysterious and unpredictable and we're all waiting to see what happens. 

Read the full story on NASA's website.  

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