Today, Comet ISON is approximately 2.21 AU from the sun. That’s over 205+ million mi (330+ million km). There are less than 90 days until ISON reaches perihelion.
Over the past 10 days, between August 20th and August 30th, Comet ISON traveled a distance of approximately 0.161 AU.
That’s an average speed of roughly 1.49 million miles per day, or 2.40 million kilometers per day.
On August 18th, the time projected (tp) value calculated by NASA for perihelion (closest to the sun) was 2013-Nov-28.78273328. That’s the equivalent of November 28, 2013 at 18:47:08 UTC.
The time projected value was updated on August 26th at 17:47:56 to 2013-Nov-28.78403051. That’s the equivalent of November 28, 2013 at 18:49:00.
Here are some news snippets from the past week.
As of today, astronomers still don’t know if Comet ISON (C/2012 S1) will put on a good show or a potentially historic one. Either way, many amateur astronomers are keen to follow it as it brightens. Join them as it comes within range of 8-inch telescopes in early September. And by month’s end, you might be able to spot it through a 4-inch scope.
“Comet ISON is paying a visit to the Red Planet,” says astronomer Carey Lisse of the Johns Hopkins University Applied Physics Lab. “On Oct 1st, the comet will pass within 0.07 AU from Mars, about six times closer than it will ever come to Earth.”
Mars rovers and satellites will get a close-up view. It’s too early to say whether Curiosity will be able to see the comet from the surface of Mars—that depends on how much ISON brightens between now and then. Lisse says the best bet is NASA’s Mars Reconnaissance Orbiter. The MRO satellite is equipped with a powerful half-meter telescope named HiRISE that is more than capable of detecting the comet’s atmosphere and tail. Observations are planned on four dates: August 20th, Sept 29th, and Oct 1st and 2nd.
— NASA, 08/23/2013 article by Dr. Tony Phillips
If anything, the new measurements should be reassuring! ISON has most definitely NOT disappeared. It has NOT fallen apart. It continues to brighten (although admittedly not as quickly as we had hoped it might when it was first discovered). In other words, it is acting like a typical new comet from the Oort cloud.
— ISON Campaign, 08/24/2013 article by Matthew Knight