Comet ISON Outburst Continues / Comet Encke Flies By Mercury This Weekend

It’s hard to believe this is the same Comet ISON as two mornings ago. This photo was taken with a 4-inch (105mm) wide-field refractor this morning Nov. 15. Click to enlarge. Credit: Damian Peach

What a horrible morning. A sky perfectly clear at 4 a.m. turned nearly overcast just in time to check out this week’s impressive outburst of Comet ISON. I did say “nearly”. Driving north to find a clearing failed, so I turned the car around and sped southeast toward Lake Superior. There along the beach, a few cracks in the clouds glided across Virgo, buoying hopes that sooner or later ISON would pop through the clouds if only for a minute.

And it did. While I could have measured the amount of time spent viewing the comet on a stop watch – maybe 3 minutes total – I enjoyed every juicy second. The head of the comet, a wimpy thing on Wednesday morning, had doubled in size and burned pale blue with a bright, intense, fuzzy center.

My pitiful attempt to record the comet this morning through clouds with a basic camera and 35mm lens. A small bluish coma or comet head is visible at the bottom of the tail. Credit: Bob King

Even through thin clouds ISON and the first half degree of its tail were easy grabs in 10×50 binoculars. Its brightness, measured on the magnitude scale, was 5.0 this morning or 2.5 magnitudes brighter than earlier in the week. That translates to a tenfold increase in brightness in just two days.

Comet ISON glows brightly in X-rays as seen by NASA’s Chandra X-ray Observatory. X-ray are given off when the comet’s neutral molecules and atoms interact with the ionized atoms of the solar wind. The picture is color-coded — yellow and red indicate greater intensity, blue less. Credit: Casey Lisse/Chandra

Around 5:15 a.m., the sky completely cleared around the comet for a single precious, complete minute. I dashed to the telescope for one last look at the bulbous blue head and tail that stretched at least a degree (twice the diameter of the full moon) up to the northwest. OK, it wasn’t such a horrible morning.

Pictures taken of both Comets Encke and ISON last week by the MESSENGER spacecraft in orbit around Mercury. Green circles are shown around cataloged background stars. Click to enlarge. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute

Today was the last for dark skies without interference from the moon. Beginning tomorrow and continuing for at least the next 10 days, the moon will light up the sky well into morning twilight and beyond. While it will make the comet difficult to see with the naked eye – assuming it doesn’t leap again in brightness – it should still be visible in binoculars. ISON is rapidly approaching the sun and will soon be difficult to see. Go out to look at it the next clear morning if you can.

You can use the map from yesterday’s blog to help you find ISON. Although low, it’s near the bright star Spica in Virgo. I’m also including a new map for amateurs willing to tackle Comet Encke, located even lower in the sky and near the planet Mercury. Encke is only a few days away from perihelion or closest to the sun. These next few days will be the last time to see the comet this apparition for northern hemisphere viewers.

You can use Arcturus and Spica in the eastern sky at dawn this coming Sunday and Monday mornings to help you find Mercury and Comet Encke. The map shows the sky facing southeast about 1 hour before sunrise. The comet is now around magnitude 6.5-7. Stellarium

7 Responses

  1. Edward M. Boll

    Do you think that the sky will be dark enough an hour before sunrise to get a last glimpse of Encke with 20 power binoculars? Using 5.0 for a magnitude for ISON this morning should bring it to about 3.8 on Monday morning.

    1. astrobob

      It’s worth a try. I’ll be out if it’s clear and will attempt it with the scope and 10x50s. By the way, check today’s blog again. I just updated it with the most amazing image of Comet ISON yet.

      1. Edward M. Boll

        It is starting to look more fan like. That is what I remember about Panstaarrs in March. I was a little depressed today. My target planet, Mercury, and stars Spica and Arcturus were bright. But, the twilight kept me from seeing any of the comets near them. I felt a little better tonight when I saw Venus shine through some clouds. It looked comet like.

  2. Edward M. Boll

    While Comet ISON seems to have flared and dimmed a bit, I doubt very much that it is at it’s end as some have speculated. The main reason, I am still optimistic about it is that there is no real proof that it has broken up. And the main reason being that if it had broken up, the seeming wings of the comet should be asymmetrical. But, they seem to be symmetrical, according to Karl Bataams, meaning that probably more dust is pouring out, and therefore it is getting more active.

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