Comet ISON May Have Survived
Nov. 29, 2013
Continuing a history of surprising behavior, material from Comet ISON appeared on the other side of the sun on the evening on Nov. 28, 2013, despite not having been seen in observations during its closest approach to 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.
Throughout the year that researchers have watched Comet ISON – and especially during its final approach to the sun – the comet brightened and dimmed in unexpected ways. Such brightness changes usually occur in response to material boiling off the comet, and different material will do so at different temperatures thus providing clues as to what the comet is made of. Analyzing this pattern will help scientists understand the composition of ISON, which contains material assembled during the very formation of the solar system some 4.5 billion years ago.
For more information on Comet ISON: www.nasa.gov/ison
To download recent ISON imagery: http://svs.gsfc.nasa.gov/Gallery/CometISON.html
NASA’s solar observing fleet to watch Comet ISON’s journey around the Sun
Posted Nov. 22, 2013 by Karen C. Fox
It began in the Oort cloud, almost a light year away. It has traveled for over a million years. It has almost reached the star that has pulled it steadily forward for so long. On Thanksgiving Day, Nov. 28, 2013, Comet ISON will finally sling shot around the sun. Here its inward journey through the solar system will end—either because it will break up due to intense heat and gravity of the sun, or because, still intact, it speeds back away, never to return.
Catalogued as C/2012 S1, Comet ISON was first spotted 585 million miles away in September 2012. Scientists were instantly intrigued, not because spotting it so far away meant it might be very bright and beautiful once it was closer to Earth—though this may indeed turn out to be the case if it survives its trip around the sun—but because this is ISON’s very first trip into the inner solar system. That means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun. Along Comet ISON’s journey, NASA has used a vast fleet of spacecraft and Earth-based telescopes to learn more about this time capsule from when the solar system first formed.
Continue Learning: http://phys.org/news/2013-11-nasa-solar-fleet-comet-ison.html
Update to Comet ISON
November 19, 2013; 12:40 PM
Recently, we have seen some changes in the brightness of Comet ISON.
Notice how the magnitude (a measure of the brightness) has gone from around 10 at the end of October to near 4 now. For the everyday person, that means that ISON has become around 200 times brighter in a matter of weeks and has been visible to the naked eye in many locations. Magnitude 6 is the general threshold for visibility to the naked eye. The smaller the magnitude number, the brighter an object is. For example, the Full Moon has a magnitude of about -12, and Venus, a bright “star,” is around -4.
So, what happened to make it so much brighter? Some scientists hypothesized that ISON has started to break up, or small fragments have broken away and that this may have caused an increase in its brightness. However, there is no hard evidence to prove or disprove that. The more likely reason is that ISON has had a series of “outbursts,” in which gases and water are expelled from the comet, which causes the brightness to go up (the magnitude down). This reason is supported by the European Southern Observatory’s TRAPPIST telescope.
To understand further what is going on now and what will happen with ISON, let’s take a look at its orbit around the sun.