Bob’s Ephemeris Blog

I can’t believe it. Here it is late October in Michigan. I’ve seen Comet Holmes each night since it’s outburst (explosion?) October 24th. We’ve been ducking clouds, but not the solid overcast that we usually have. To the unaided eye, it’s a bit fuzzy and still by a small measure is still the third brightest object in the constellation of Perseus. In the evening it’s about half way between the W shaped constellation of Cassiopeia high in the northeast and the bright star Capella much closer to the horizon below it. It is a pretty good size fuzz ball in binoculars. In a telescope, the big circular head or coma of the comet contains an off center bright plume with the bright comet nuclear region to one side. So there appear to be three components to the comet. All in all it’s been the weirdest comet I’ve seen. Spaceweather.com has some great pictures of the comet.

Scott Anttila emailed some pictures to me with this message early Tuesday:

Well I got out again last night for some images. The exposure times have been climbing, 750 ms the first night 20 seconds last night. So total magnitude is steady, while as Bob suggests, surface brightness is dimming as the comet expands. To the unaided eye last night the comet looked, well, like a comet. I wish I could see a tail off the back. At this rate I would guess the outer portions of the coma will soon fade from view in small telescopes, hey but what do I know. I hope we get another partly clear night in the next week or so.

Here’s an animation showing the comet’s increase in size after the outburst.

Here’s some thumbnails of other images he included. Click on them for a larger image.

Tags: Observing, Astrophotography, Scott Anttila, Comet by Bob Moler
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My first view of Comet Holmes tonight showed it still growing. I’me getting the impression that it’s surface brightness is dropping and it increases its size. This seems to be true, because its total brightness is holding up. Comet Holmes is still the third brightest “star” in Perseus, though it seems to be giving Algol a run for it’s money tonight. Algol is at full brightness. This eclipsing variable star will go through it’s minimum brightness until after sunrise tomorrow. Then for those more than a few hours west of here will see Comet Holmes shine brighter than Algol.

It now mostly fills my 74 power eyepiece. It’s also passing in front of another star tonight. Last night’s passage of the comet in front of some stars got a lot of us thinking “splitting Nucleus”, but no. I gotta remember the comet’s now seen against the Milky Way. It’s going to be more so in a week or so, because the comet’s heading for the Alpha Persei Association. It’s a rich field of stars just below unaided eye visibility. Binoculars will show a marvelous star field here rivaling the Pleiades. Comet Holmes will cruise right in front of it.

Last Saturday’s finder chart will still get you close enough to the comet for the next week.  Just ignore the moon, which has moved on.

Tags: Observing, Comet by Bob Moler
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Last night Richard Kuschell called and said he’d be downtown Traverse City near Horizon Books. I found him setting up his telescope. I was outside checking out the comet with my granddaughter at the time, so when we were finished, I packed up my telescope and headed down there. It was rather hard to locate the comet downtown. I usually try to locate the comet by first locating alpha Persei (Mirfak), but I happened to run into the comet first with my finder. It’s quite distinctive with it’s tiny disk. We attracted a steady crowd, only a few of which knew of the comet.

I received an email earlier today from Scott Anttila, who has better eyes than I. He mentioned that the comet was visible as a fuzzy spot to the unaided eye. I He also enclosed this comparison photo of the comet’s appearance on Thursday and Saturday nights.

The comet is slow moving, so it’s position is close to those of the prior chart which I repeat below.

8: 30 p.m. Update:

Scott called and told me that he was informed by someone with a 16″ telescope that he was seeing two nuclei. I had seen the comet earlier with my 11″, but at low power. I hauled the telescope out again and checked the comet with higher power. Sure enough there were two star like objects embedded in the central bright spot of the comet. One was near the center, while the other was near the edge of the central glow.

This probably means that the nucleus of the comet has broken into two pieces. This explains the sudden brightness of the comet. All that fresh surface area exposed to the sun, would do it. Last year we had the passage of a broken comet Schwassmann-Wachmann 3. It had broken into multiple comets a few years ago. Before that one of the many comet LINEARs just flat disintegrated into a million pieces. My first encounter with a broken comet was Comet West in 1976. This rather mediocre comet’s nucleus broke into 4 pieces as it approached its closest point to the sun. That comet turned out to be spectacular in the morning sky.

A split nucleus means that the comet will continue to be super bright for quite a while.

1:15 a.m. October 29 Update

 Scott may be right about the background star.  Alas, a split nucleus would explain so much.  But, as they said before the days of digital photography:  Let’s see what develops.

Tags: Observing, Scott Anttila, Comet by Bob Moler
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I got a break in the clouds just after 11 p.m. tonight the sky was a bit hazy, but the comet was visible to the unaided eye, barely, with the bright moon out. In binoculars, the comet is no longer star like. A small disk can be perceived.

The comet was noticeably bigger in the telescope too. The extremity of what I take to be the coma or head of the comet is a not as sharp as it was last night. The bright nuclear region is shifted west of center, as I saw at midnight this morning. I was also seeing, with averted vision some dim haze outside the coma to the north. Cartes du Ciel wants the tail to go to the south, and be very foreshortened since the phase angle is only 16 degrees. The directions I got from the telescope may be in error since I was converting altazimuth motions to equatorial.

Below is a finder chart for tomorrow night. This comet is a long way from us and the sun, 1.6 and 2.4 AU a piece, so it’s moving slowly in retrograde, or westward. 1 AU is 93 million miles, the distance from the earth to the sun. The comet is moving slowly in actuality too. It has an eccentricity of only 0.43, rather small for a comet. It stays around the asteroid belt.

The chart was created with Cartes du Ciel.

Tags: Events, Observing, Comet by Bob Moler
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Here’s what Scott has to say:

The comet as an extra star in Perseus, sitting just below and west of Mirphak. It was brighter then I though it would be. With a 76mm reflector I was able to see what looked like a planetary nebula, nebulosity around a brighter central point. Through my 12″ scope a central bright point became visible with what looked like a short tail pointing east all surrounded by a large nebulosity. Looks as though the comet is coming nearly directly at us or moving nearly directly away from us. (The photo below was) Taken with a Canon 350D combination of 40 1 second exposures ISO 800 and ISO 1600. Through a 8″ f/5 Newtonian.

Tags: Astrophotography, Scott Anttila, Comet by Bob Moler
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I’ve got my 11″ Dobsonian cooling down, awaiting the darkness. Scott Anttila, 30 miles east of me is setting up three telescopes tonight. I’m sure this is being repeated word over as night falls.

At two this morning I went out as the sky was clearing and easily spotted the comet, nearly overhead at that hour. It did have a yellowish cast, and unlike my Ephemeris report this morning it was the third brightest star in Perseus not the fourth. Below is a chart I created for tonight.

Comet Holmes position for 10/25/07 (Tonight) in the evening - Eastern time. The little comet symbol has a tail, though the comet may not. To the unaided eye or binoculars the comet is star like. It’s 1.6 times the distance of the sun from us, so it’s much farther than most bright comets. The chart was produced using Cartes duCiel.

This entry will be updated after I check out the comet tonight.

Update 10 p.m.:

The comet is definitely strange looking. It’s stellar in appearance to the unaided eye. In binoculars, there’s a hint that it may not be stellar. Below is my impression through a telescope:

The evenness of the brightness of the large disc, and the rather sharp edge was surprising. The edge appeared a bit brighter than the disk itself. This is the coma or head of the comet. The nucleus, the solid part of the comet is hidden in the bright nuclear region in the center. I was expecting something more fuzzy and more asymmetrical. There was a hint of a bright streamer extending outward from nuclear region, to the south, but I really couldn’t capture it on this drawing in its subtlety. At high power there was a ring of a dim glow surrounding the coma, but it was ill defined. www.spaceweather.com along with the sites on the blogroll on the right for more information.

Color images of the comet show the disk to be yellow from dust reflecting sunlight with a green core of bright gas. There’s a growing gallery on www.spaceweather.com.

 Update Midnight:

The comet’s appearance has changed.  The nucleus is now off center to the west.  Other than that there’s not much change.  The changing location of the nucleus is probably due to it’s rotation.  We’ll see.

Tags: Events, Observing, Comet by Bob Moler
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I just found this on the Sky and Telescope web site. Comet Holmes an old periodic comet has brightened from 18th to 3rd magnitude. It may stay that way for some days. Here’s a finder chart with tonight’s (October 24th, 2007) and Monday’s (October 29th, 2007) positions.  It’s within the curve of the end of the constellation Perseus.  This constellation is low in the northeast in the evening below the ‘W’ shape of the constellation Cassiopeia, rising to be nearly overhead near dawn.

The chart above is by Cartes duCiel.

Tags: Events, Observing, Comet by Bob Moler
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I guess I’m showing my age, but it’s been nearly 22 years since I’ve seen the most famous comet of then all: Halley’s Comet. It wasn’t particularly spectacular. Hale-Bopp’s appearance of 10 years ago was everything Halley was not.
Hale-Bopp won’t be back for 2,000 years, but Halley will be back much sooner, only 54 years from now. I don’t think I’ll make it till then. There’s not too many people who’ve been fortunate to have seen Halley’s Comet twice.
So what’s with the title? This month the earth will pass through the debris trail left by Halley’s many returns to the sun. Halley’s returns to the sun have been traced back to perhaps 2467 BC thanks to Chinese records. It’s been recorded on 29 appearances since 240 BC. For those of us who saw the 1986 appearance of the comet, Halley’s wasn’t the great comet noted in the pass. Of course the earth wasn’t in the greatest position to view the comet that year.

All this month, peaking around the 21st, the earth will sweep into the tenuous trail of debris from the comet. As seen from the orbital track on this page the orbit of Halley’s Comet passes near the earth’s orbit on two points. On the way in it crosses the earth’s orbit where the earth is around October 21st. On the way out it crosses much closer to the earth near May 9th. The first, not so close passage causes the Orionid meteor shower, which gives us at best about 20-25 meteors an hour. The second is the Eta Aquarid meteor shower; which isn’t easily seen from the northern hemisphere, but rivals the Perseids in numbers of up to 50 meteors per hour for those in the southern hemisphere.

On the morning of the Orionid peak, October 21st, the gibbous moon will set about 2:12 a.m., leaving the sky dark until twilight starts at 6:26 a.m. The radiant point for these meteors is from the upraised club of Orion, as can be seen on the chart above.

The bits of Halley’s Comet will streak through the sky at 66 kilometers per second or 41 miles per second to burn up high overhead. So yes you can see bits of Halley’s comet this month.
Halley’s Comet’s fame began when it was rediscovered on December 25th, 1758. It proved British astronomer Sir Edmund Halley’s calculations were correct. He observed the comet in 1682 and noticed that its appearance was close to the of the comets of 1531 and 1607 that returned at intervals of 75 to 76 years. He predicted that that comet would return in 1757, The comet was delayed, but arrived to be found the next year.

Comets and their debris trains get batted around by gravitational forces of Jupiter and the rest of the planets. In fact Jupiter is responsible for most of the periodic comets there are. Interestingly, the Orionids seem to have a periodicity in strength of about 12 years. This was discovered by Audrius Dubietis of Vilnius University, Lithuania. Could it be related to Jupiter and it’s 12 year orbit of the sun? Halley’s Comet does come reasonably close to Jupiter’s orbit on its inbound leg. The last bit is my own thought. 2008 to 2010 the Orionids are expected to be near peak strength in this 12 year cycle.

From the orbital chart above, Halley’s current orbit doesn’t come particularly close to the earth. It passes at 0.15 AU from the earth, That’s about 14 million miles. However in 1911 Charles P. Olivier noted that the Orionids had similar orbits to those of the Eta Aquarids. The link of the Eta Aquarids to Halley’s comet had already been established. But still 0.15 AU is a wide miss of the earth. Astronomers B.A. McIntosh and Hajduk worked from Halley’s orbital data all the way back to 1404 AD from Donald K. Yeomans and CAT Kiang and were able to prove the connection with Halley’s Comet.
The Orionids can be surprising in another way. It has been noted on other appearances that sometimes it has more than one peak. Several times a peak on the 18th was as strong as the one on the 21st.
The Orionids aren’t the only meteor shower in October. There’s the very intense, on occasions, Draconids. These are related to Comet Giacobini-Zinner, and occur on October 8th or 9th. Their last big return was in 1998, The comet has an orbit of the sun of about 6 ½ years. We don’t get a great shower every time the comet returns.
Next month are the famous Leonids around the 17th of November. The next and last outburst of more than normal numbers of meteors will be in 2009. This year should be a normal Leonid year. This shower is related to Comet Tempel-Tuttle, in a 33 year orbit of the sun. If I’m counting right it’ll be back in 2031.

Tags: Events, Observing, History by Bob Moler
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Tomorrow morning we’ll see the peak of the Draconid or Giacobinid meteor shower. On most years it isn’t much, as is this year. There was a minor outburst two years ago. The comet has a 6.6 year orbit of the sun, and won’t come really close to the earth again until 2018 at 0.38 AU. An even closer approach to Jupiter in 2029 will move the comet farther from the earth’s orbit. See Gary W. Kronk’s Cometography site.
The radiant for these meteors is the head of Draco the dragon, just north of the bright star Vega.

Tags: Events, Observing by Bob Moler
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50 years ago the Soviet Union scooped the United States and put an artificial satellite in orbit of the earth. It was called Sputnik, Russian for companion. It sole purpose was to emit radio beeps, announcing “I am here!” It indeed did that, and gave the US an enormous inferiority complex. How had we failed? Were we teaching our kids enough math and science? Trouble is, we’re still asking that question 50 years later. I was already an amateur astronomer in those days, in the 11th grade and a member of the Grand Rapids Amateur Astronomical Association and its Junior club.

The first 15 years from 1957 to 1972 were a heady time. A dog was sent on a one way ride in space a month after Sputnik 1. On January 30th, 1958 the US sent a 30 pound satellite christened Explorer 1 with a real scientific instrument aboard with which James VanAllen discovered the radiation belts that now bear his name. By Christmas the US orbited an entire Atlas rocket taking the weight record. In 1958 the Soviets returned the first pictures from the far side of the moon. In 1961 humans entered spade, with Yuri Gargarin’s orbit and Alan Shephard’s 15 minute ride. It was that year President Kennedy laid down the challenge of putting man on the moon by the end of the decade. In short order the US sent successful probes to Venus and Mars. The manned program progressed from Mercury, Gemini to Apollo, when the Apollo fire and the death’s of three astronauts slowed the program. But after an inspirational reading of Genesis from lunar orbit by the Apollo 8 crew on Christmas Eve, the program was again on track. This culminated with the landing of Neil Armstrong and Edwin (Buzz) Aldrin on the moon on July 20th 1969.

It started to go downhill from there. Yeah, we won the space race! Can we go home now? That seemed to be the sentiment of Congress. Six more expeditions to the moon were launched. Five made it. When we finally got a real scientist on Apollo 17, the program was cancelled.

To me the real promise of the space program is those robot emissaries with the names Pioneer, Mariner, Viking, Voyager, Galileo, Cassini, Magellan, Hubble and others going where no one has gone or possibly will go.

The following statement may get me into trouble, but what the hell. The space shuttle, and the International Space Station are for the most part a waste of money. The programs of the last paragraph spent a small fraction of the amount of these and returned many more times the knowledge.

Go Robots!

Tags: History, Anniversary, Commentary by Bob Moler
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