Comet ISON is every day more and more closer to the Sun, and with every new day it reveals more new details. More astronomers report clearly visible double tail feature. Primary ion gas tail developed a dust tail companion so now Comet ISON is double tail comet.
Primary tail is in fact ionized gas pushed away from the comet by solar wind and it always points almost directly away from the Sun. The other tail is the dust tail which traces the comet's orbit and does not point directly away from the sun as the ion tail does.
One of the first images that showed double tail feature was taken by Damian Peach on November 6, 2013 (Credit: Damian Peach)
In the meantime, NASA's Chandra X-ray observatory, ninth spacecraft that is now observing Comet ISON, captured first X-ray image of comet on November 3, 2013, detected in the ACIS-S low resolution spectro-photometer. The morphology looks pretty normal, with maximum brightness closest to the nucleus, but a bit offset towards the Sun. Only in the past 20-years have we known that comets emit X-rays, so seeing ISON shining brightly at these wavelengths is very exciting. If the comet survives its close encounter with the Sun, another X-ray imagers on the NASA MESSENGER spacecraft could take more interesting shots.
Chandra X-Ray Telescope observed Comet ISON on November 3, 2013. (Credit: Casey Lisse/CIOC/Chandra)
ISON is now inside the orbit of Venus and it is currently moving through the constellation Virgo low in the eastern sky before dawn. It is moving extremely fast now at around 50 km/s (180 000km/h, 112 000mph), and approaching twilight skies so it will become increasingly difficult to observe. ISON is now shining as bright 8 magnitude star
The latest light-curve for Comet ISON (compiled November 11, 2013 by Matthew Knight).
Location of Comet ISON on November 12, 2013 in relation with STEREO Ahead and STEREO Behind spacecrafts, Mercury, Venus and Earth (Credit: NASA/STEREO)
At its closest approach it will be 64 million km (40 million miles) from Earth, just under half the distance between our planet and the Sun.