Today, Comet ISON is approximately 2.602 AU from the sun. That’s over 241+ million mi (389+ million km). There are less than 115 days until ISON reaches perihelion.
Over the past 5 days, between July 31st and August 5th, Comet ISON traveled a distance of approximately 0.074 AU.
That’s an average speed of roughly 1.375 million miles per day, or 2.21 million kilometers per day.
On July 29th, the time projected (tp) value calculated by NASA for perihelion (closest to the sun) was 2013-Nov-28.77833189. That’s the equivalent of November 28, 2013 at 18:40:47 UTC.
ISON is currently between the orbits of Mars and Jupiter, but from Earth’s perspective, it appears behind the Sun’s glare. ISON entered the Sun’s glare back in June and should become observable by NASA’s equipment in mid-August or early September at the latest. It’s projected that it will become visible to the naked eye by early to mid-November.
Here are some news snippets from the past week.
“On Aug. 10, Comet ISON will be 18.1 degrees from the sun and will begin rising above the east-northeast horizon before dawn,” Rao wrote earlier this week. (Your clenched fist held at arm’s length measures about 10 degrees.)”
For mid-northern latitudes on the morning of Aug. 21, ISON will stand 6 degrees above the east-northeast horizon at the start of twilight,” Rao added. “And by the end of August, the comet’s altitude will double to 12 degrees by the time dawn begins to break, making it an easy target for skywatchers.”
…But it’s not clear just what skywatchers will see, Rao and others stress.
Will comet ISON blossom into a naked-eye comet, sporting a long, beautiful tail across the sky? Comets are notoriously unpredictable and can surprise even experts. Unfortunately, it’s now a wait-and-see game since the comet is currently lost in the glare of the sun and will only be visible again in early September.