Zodiacal Light and the Phantom Comet


Zodiacal Light at Dawn from New Mexico (Dec 2013)

The Zodiacal Light shines bright in the New Mexico dawn, near where the ill-fated Comet ISON would have been.

This was the dawn sky on the morning of December 6, 2013 looking east from our observing site at the Painted Pony Resort in New Mexico.

The zodiacal light was bright pre-dawn extending up from the horizon to high overhead. This glow is from sunlight reflected off comet dust in the inner solar system.

Adding to that cloud of dust is presumably the remains of Comet ISON (C/2012 S1) – this image includes the position where ISON would have appeared had it survived, with its head left of centre, just left of the zodiacal light, and just above the mountain ridge. Its tail would have arched up and to the left, had it grown an extensive dust tail as was hoped.

As it is, there is a comet in the field – Comet Lovejoy (C/2013 R1) is a tiny blue blip at far left, a minor consolation prize for missing ISON. Pity ISON didn’t work out, as we would have had two photogenic and naked eye comets in the dawn sky together.

The field also contains two planets: Mars in Leo above and right of centre, and Saturn in Libra just coming up over the mountains in the middle of the zodiacal light. Both lie in the zodiacal light because the light follows the ecliptic – i.e. the plane of the solar system and the orbits of the planets.

– Alan, December 6, 2013 / © 2013 Alan Dyer

Comet ISON at Perihelion (Actual vs. Predicted Paths)


 

I superimposed the actual footage of Comet ISON passing by the Sun onto a graphic simulating its predicted path around the Sun at perihelion. They match!

This is an animation of Comet ISON at perihelion. I superimposed the actual SOHO satellite movie footage, released Friday, Nov 29, onto a still-image sky background (created with Starry Night™ software) that shows the scene at the moment of perihelion, and that displays the predicted orbital path of ISON plus labels the stars.

You’ll see the star fields (real and simulated) register fairly closely (check Antares at lower left) around the time of perihelion. It’s neat how the comet follows its predicted path! Well, of course! Newtonian gravity stills rules the solar system.

But I am amazed at how well the simulation (which is done from the viewpoint of the surface of Earth) lines up with the real movie (which was taken by the SOHO satellite from the L1 point 1.5 million km away from Earth but in the Earth-Sun line).

Click here for a more recent version using the SOHO footage released November 30, available at my Flickr site

— Alan, November 29, 2013, revised Nov. 30 /with credit to StarryNight™/Simulation Curriculum and to NASA/ESA

Sundiving Comet ISON – A Last Look


Comet ISON C/2012 S1 (Nov 21, 2013)

Comet ISON performs its dive toward the Sun, caught in the morning twilight.

This was the infamous and much-hyped Comet ISON (C/2012 S1) as it appeared this morning, November 21, 2013, a week before it performs its hairpin turn around the Sun.

The comet was easy to see in binoculars, though the camera picks up a bit more of its faint tail. ISON was much more photogenic a week ago when it was higher in a darker and moonless sky. But this morning I had to contend with bright moonlight from a waning Moon and the brightening dawn. The inset shows a blow up of just the comet.

ISON is dropping rapidly toward the Sun, making this perhaps the last sighting I’ll have of it until it reappears – we hope! – from behind the Sun in early December. If it survives its perihelion passage it might blossom into brilliance … or fade into obscurity. No one knows.

In the photo above, you can see Mercury at left, shining much brighter than ISON. It was brilliant as it rose into the southeast sky, with the elusive planet now about as well-placed as it gets as a “morning star” for us living at northern latitudes.

Comet Lovejoy C/2013 R1 (Nov 21, 2013)

This morning I was able to shoot not one but two comets.

About half an hour before ISON hove into view I aimed the camera up almost overhead toward Ursa Major, to capture Comet Lovejoy (C/2013 R1) as a bright cyan fuzzball with a short tail. Again, the photo brings out the tail – to the eye the comet was obvious in binoculars but appeared as just a fuzzy star.

I took both shots with the same gear: a 135mm telephoto lens on the Canon 5D MkII on an iOptron SkyTracker. The Lovejoy shot is a stack of 5 x 75 second exposures. The ISON shot is a 4-second exposure, with the colours and contrast boosted for prettiness.

This is certainly proving to be a year of comets. It would be nice if just one of them got really bright!

– Alan, November 21, 2013 / © 2013 Alan Dyer

 

Comet ISON Passes Mars


Comet ISON & Mars (Oct 8, 2013)

Comet ISON passes Mars on its inbound journey toward the Sun.

This was the scene on the morning of October 8, 2013, with Comet ISON (top), still small and faint, passing the planet Mars, the bright object at bottom. The comet was actually close to Mars in space in addition to appearing close to Mars in our sky.

Comet ISON is the much-heralded “comet of the century,” but so far has failed to live up to expectations. It may never become visible to the unaided eye. Or it could blossom into a dawn spectacle after it rounds the Sun on November 28.

Only time, and the vagaries of comets, will tell.

This image is a stack of five 5-minute exposures with a 92mm aperture refractor and Canon 5D MkII at ISO 1600.

– Alan, October 8, 2013 / © 2013 Alan Dyer