Newly-discovered Comet ISON is headed our way and is causing a bit of buzz. Astronomers are pretty sure that it will be visible to the naked eye and from the northern hemisphere. It also has the potential to be spectactular next autumn.

But if you've been reading about this, save the excitement for later. A Sky News headline reads "Newly-Discovered Comet May Outshine The Moon". True, but it also may fail to outshine the Moon. It might even break up like Comet Elenin without any but the most dedicated having seen it at all.

Comets are notoriously unpredictable!

The comet doesn't look like much now - just a faint object in the constellation Cancer. However it is larger and its orbit is expected to take it close to the Sun next autumn.

I hope ISON doesn't fizzle like Kohoutek in 1973.

Absolutely right, Jim. Kohoutek should be a warning to anyone announcing that a spectacular comet will be gracing our skies.

But I really hope this one lives up to its promise, since it would be visible in the northern hemisphere. I'm still feeling aggrieved about Comet McNaught - the Great Comet of course, as McNaught is always finding comets.

I have only seen 3.

Ikeya-Seki in 1965
Hyakutake in 1997
Hale-Bopp in 1997

I saw both in 1997 - that was a great year for comets! I loved them both.

Comet ISON has now been picked up in good amateur telescopes with good viewing conditions, but it is still quite far away. It will be passing Mars within the month and it may be that we'll get a good view from there.

But in November, if it brightens - and, importantly, isn't destroyed as it grazes the Sun - it could be very bright indeed in November.

Or it could just fizzle out. Fingers crossed.

I loved looking at Hale-Bopp.

Oh yes, Connie, Hale-Bopp was great. None of this looking through binoculars for some vague fuzzy thing and wondering if that were the comet. When you saw Hale-Bopp that was really obviously the comet.

This seems to have been taken earlier this evening using a remote telescope on Teide, Canary Islands: Comet ISON 2013-09-09.

The Mars Reconnaissance Orbiter did get a few snaps of Comet ISON. They show the comet as smaller than expected and also not as bright as expected. This doesn't mean that it won't be a naked-eye object as it nears the Sun, but it cuts down the chances.

Astronomers around the world are getting some nice pictures of it. Here's one from Germany: Comet ISON

The NASA Comet ISON Observing Campaign reports that the comet is still in good shape. It looks likely to reach perihelion (when it's closest to the Sun) without fragmenting. But no one can say what will happen then.

Here is a picture taken on October 8th by Adam Block. Comet ISON seen from Arizona Block, by the way, was one of the winners in the Astronomy Photographer of the Year Competition 2013.

Comet ISON is a sun-grazing comet, meaning it will get quite close to the Sun, something which many sungrazers don't survive. Here is a very good 3-minute video that explains what a sun-grazing comet is.

Video: What is a sun-grazing comet?

The comet looks a blue-green color because some of the gases that surround its nucleus glow green when heated by the Sun. One of the gases is poisonous cyanogen, but don't worry. The comet doesn't come near Earth and the gas is very diffuse.

Recent pictures of Comet ISON and spectrum

Comet ISON has not exactly been looking like the Comet of the Century. However reports were that it did suddenly brighten yesterday - enough to be just visible without binoculars if the sky conditions are good.

I haven't been encouraged by its showing so far, so haven't got up before sunrise to have a look. But a colleague has done so. He saw Comet Lovejoy through binoculars the other morning, but ISON was lost in low clouds. This morning he saw something fuzzy through thin cloud where ISON should be, suggesting that the comet had indeed brightened.

Here is a photo taken yesterday morning showing the brightening. The comet has also developed an ion tail in addition to the dust tail.

Completely clouded over where I am, but here is a report from SpaceWeather.Com: "Experienced observers put the comet's magntitude at +5.5 on Nov. 16th, which is fully 10 times brighter than it was only three days ago before the outburst. To the naked eye, ISON appears as a faint smudge of pale green light low in the pre-dawn sky. The view through a telescope is more dramatic. The comet's tail has become a riotous crowd of gaseous streamers stretching more than 3.5 degrees across the sky."

Here is a photo from Amateur astronomer Waldemar Skorupa in Kahler Asten, Germany: Comet ISON with fabulous tail.

This is a beautiful dawn picture of Comet ISON and in the middle the planet Mercury. The comet was just barely visible to the unaided eye, but a small telephoto lens captured it amid the glorious colors of sunrise over Gran Canaria.

This little video is about how the Sun cooks a comet as it comes into the inner Solar System. NASA's not really suggesting that Americans cook a comet for Thanksgiving instead of the usual: How to Cook a Comet

Note to educators (or anyone else who's interested): You can download the video from this page.

Comet ISON is now very close to the Sun. Its perihelion (closest approach to the Sun) is on Thursday, Thanksgiving Day in the USA. It's already too close for keen astronomers up before dawn to photograph. But we're still able to observe the comet as it heads for its rendezvous with the Sun, because of Sun-watching satellites.

Several days ago the STEREO hi-res camera caught both Comets ISON and Encke.

Yesterday Comet ISON, on its way to perihelion (nearest approach to the Sun), came into the field of view of SOHO. SOHO is the Solar and Heliospheric Observatory of NASA and ESA (European Space Agency). Today - Thanksgiving Day in the USA - sungrazer ISON will be as close as 730,000 miles above the Sun's surface.

Here is the SOHO image of Comet ISON

It looked as though Comet ISON had broken up during its closer encounter with the Sun. It disappeared from the SOHO field of view and couldn't be found again. But then it was found! It seems that at least a part of the nucleus had survived. But I've just checked Spaceweather.com and the latest is that the surviving part of ISON is dissipating.

Here are pictures from Solar and Heliographic Observatory (SOHO).

ISON has twice been declared dead. I wonder what the news will be tomorrow.

I thought I should end this year-long saga by noting that ISON definitely didn't survive its trip around the Sun. That's official. Not the Comet of the Century after all. Once again, we see the unpredictability of comets. Still hoping for another Hale-Bopp! You can see some pictures on comets on my Comets Pinterest board.