Friday, November 29, 2013

Comet ISON Fizzles As It Rounds The Sun

As ISON appeared to dim and fizzle in several observatories and later could not be seen at all by NASA's Solar Dynamics Observatory or by ground based solar observatories, many scientists believed it had disintegrated completely. However, a streak of bright material streaming away from the sun appeared in the European Space Agency and NASA's Solar and Heliospheric Observatory later in the evening. The question remains whether it is merely debris from the comet, or if some portion of the comet's nucleus survived, but late-night analysis from scientists with NASA's Comet ISON Observing Campaign suggest that there is at least a small nucleus intact.

Comet ISON went around the sun on Nov. 28, 2013. Several solar observatories watched the comet throughout this closest approach to the sun, known as perihelion. While the fate of the comet is not yet established, it is likely that it did not survive the trip. The comet grew faint while within both the view of NASA's Solar Terrestrial Relations Observatory, and the joint European Space Agency and NASA's Solar and Heliospheric Observatory. The comet was not visible at all in NASA's Solar Dynamics Observatory.

These images from NASA's Solar Terrestrial Relations Observatory and the ESA/NASA Solar and Heliospheric Observatory show Comet ISON growing dim as it made the journey around the sun. The comet is believed to have broken up and evaporated.

Image Credit: NASA/SDO/ESA/SOHO/GSFC

"We didn't see Comet ISON in SDO," said Dean Pesnell, project scientist for SDO.

"So we think it must have broken up and evaporated before it reached perihelion."

This image from NASA's Solar Dynamics Observatory shows the sun, but no Comet ISON was seen. A white plus sign shows where the Comet should have appeared. It is likely that the comet did not survive the trip.

Image Credit: NASA/SDO

While this means that Comet ISON will not be visible in the night sky in December, the wealth of observations gathered of the comet over the last year will provide great research opportunities for some time. One important question will simply be to figure out why it is no longer visible.

Comet ISON at 9:30 a.m. EST on Nov. 28, 2013

Comet ISON moves ever closer to the sun in this image from ESA and NASA's Solar and Heliospheric Observatory, or SOHO, captured at 9:30 a.m. EST on Nov. 28, 2013. This image is a composite with the sun imaged by NASA's Solar Dynamics Observatory, or SDO, in the center, and SOHO showing the solar atmosphere, the corona. 
Credit: ESA&NASA/SOHO/SDO

Comet ISON at 10:51 a.m. EST on Nov. 28, 2013

Comet ISON has moved quite close to the sun in this image from ESA/NASA's Solar and Heliospheric Observatory captured at 10:51 a.m. EST on Nov. 28, 2013. This image is a composite, with the sun imaged by NASA's Solar Dynamics Observatory in the center, and SOHO showing the solar atmosphere, the corona. 

Credit: ESA&NASA/SOHO/SDO


Contacts and sources:
Karen C. Fox
NASA's Goddard Space Flight Center

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