Camelopardalid “No-show”?

Camelopardalids… more like the Camelopardaliduds or the Camelordalididn’ts.

Last weekend’s much anticipated Camelopardalid meteor shower from comet 209P/LINEAR was a big disappointment for most meteor watchers. Rather than ZHRs of 100-400, the peak ZHR only reached ~15 per hour. Making things even worse, the ZHR rate is not the rate of actual visible meteors (ZHR is meant for comparing different showers under different observing conditions; ZHR is an idealized rate only valid for observers under very dark skies and with the radiant overhead). Still a Camelopardalid ZHR of 100-400 should have produced 15-60 meteors per hour for the average observer. The actual ZHR of 15 means that most people saw a couple of Camelopardalids per hour at most.

Before going into what went wrong, let’s look at what we got right.

Comet 209P/LINEAR does produce meteors and, in particular, laid down a number of dust trails that caused a meteor outburst. In fact, the predicted time of for crossing the dust trails appears to have been spot on.

What went wrong? Obviously our understanding of the properties of the dust of 209P and perhaps even their exact location in space was wrong. The dust the Earth encountered was smaller than expected. Combine that with slow encounter velocities (19 km/s) and you get a shower that produced meteors that were too faint to be seen visually. Meteor radar observatories such as the Canadian Meteor Orbit Radar and the Japanese Radio Meteor Observatory saw many more meteors in the 6th to 7th magnitude range.

In short, the biggest problem was that we were going into this shower blind. For a few years around 2000, very accurate predictions of the Leonids were made. But these predictions had the benefit of centuries of positive (and negative) observations to better quantify the number of meteors that could be seen. The Camelopardalids had no ‘back catalog’ of meteor outbursts. Not only were no outbursts observed prior to this year but the parent comet was only discovered in 2004. So we had no knowledge of how active, or even if the comet was active at all, prior to discovery.

For the people who study meteor showers and their parent comets, the shower (dud or not) was a learning experience and the data we collected is still very useful. 209P is making a very close approach to Earth (~0.06 AU tonight) and it is almost unprecedented that we can observe such a low-activity comet this close.

For more analysis and some early results on the shower, check out the pages by Peter Jenniskens and Sky and Telescope.

 

209P/LINEAR and this weekend’s Camelopardalids

This Friday evening/Saturday morning meteor watchers in Canada, the United States and Latin America may be treated to a meteor outburst from a rarely seen meteor shower. There is a possibility that dust from short-period comet 209P/LINEAR will produce a nice meteor shower.

There has been plenty already written on this possible shower, so I’ll just list a few sites that you should definitely visit.

American Meteor Society – where, when and how to observe the shower

Peter Jenniskens Meteor blog – the latest on what we know about the shower and its parent comet

International Meteor Organization – up-to-date activity graphs

The parent comet, 209P/LINEAR, is making a close approach to Earth this month. In fact at a little over 0.05 AU from Earth, 209P will be making the 9th closest known approach of a comet to Earth. Unfortunately it is very low activity comet and only observers with very large backyard telescopes will be able to see it. The movie below was made by myself only a few days after the comet’s perihelion.

Comet 209P/LINEAR as seen with the Vatican VATT 1.8-m telescope on 2014 May 9 UT in images by Carl Hergenrother.

 

In the Transient Sky – February 2012

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of February 2012.

February 2012 Highlights
* Venus and Jupiter share the evening sky
* Mars brightens as it approaches opposition
* Comet C/2009 P1 (Garradd) is a nice binocular object during the morning

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Mercury – Mercury makes an evening appearance during the later half of February. Find Mercury ~30° to the lower right of Venus. The Moon will be close to Mercury on the 22nd.

Venus – Venus is the brilliant beacon in the southwest after sunset. As bright as Venus is it will only get brighter and higher in the sky for the remainder of the winter and into the spring. This year’s evening apparition is as good as it gets with peak visibility in March/April. The real showstopper occurs at the end of the apparition in June when Venus will transit the disk of the Sun. This will be the last Venus transit till 2117. The Moon and Venus make a gorgeous pair on the evening of the 25th.

Jupiter -  The King of Planets shares the evening sky with Venus. It is high in the southeast sky at the end of evening twilight. Past its late October opposition occurred it will slowly fade from magnitude -2.6 to -2.3. Located in Aries, Jupiter will appear to slowly drop lower in the sky and closer to Venus as the month progresses. On Feb 1 Jupiter and Venus are separated by 40°. This distance will shrink every night and by the end of the month they will only be 12° apart. Not that you’ll need the Moon to find Jupiter but the two will make a nice pair on the nights of the 26th and 27th.

Morning Planets

Mars - With opposition in March 2012, Mars double in brightness (magnitude -0.5 to -1.2) as it begins to retrograde near the Leo-Virgo border. Mars rises around 9 pm on the 1st and 7 pm on the 29th. The Moon pairs up with Mars on the morning of the 9th and 10th.

Saturn - Saturn rises three hours after Mars. At magnitude +0.5 Saturn will be located ~7° to the lower right of the slightly fainter star Spica in Virgo (magnitude +1.0). The Moon visits on the morning of the 12th and 13th.

Meteors

Meteor activity starts off high at the beginning of the month but then drops quickly as the month prgresses. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During January mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion occured 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and is already a borderline naked eye object for observers at very dark sites. I was able to observe the comet on the morning of January 2, 2012 with 10×50 binoculars and estimated its brightness at magnitude 6.7. The comet should only be a little brighter this month.

The comet starts the month at a distance of 1.64 AU from the Sun and 1.55 AU from Earth. At mid-month it is 1.71 AU from the Sun and 1.38 AU from Earth and by month’s end it will be 1.80 and 1.28 AU from the Sun and Earth, respectively.  Though the comet is post-perihelion and moving away from the Sun, it is also moving closer to Earth. As a result, the comet should peak in brightness this month.

Traveling north from Hercules through Draco, Comet Garradd is best in the early morning though it will be a circumpolar object by the end of the month.

Date       RA       DEC     Delta    r    Elong   Mag
Feb 1    17h 17m  +41°17'   1.548  1.642    77    6.5
Feb 15   16h 51m  +52°20'   1.377  1.714    91    6.4
Feb 29   15h 33m  +65°10'   1.275  1.802   105    6.5

Small Telescope Comets (V = 8.0 – 10.0)

None

In the Transient Sky – January 2012

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of January 2012.

January 2012 Highlights
* Venus and Jupiter share the evening sky
* Comet C/2011 W3 (Lovejoy) remains a nice, though fading, naked eye object for southern observers
* Comet C/2009 P1 (Garradd) is a nice binocular object during the morning
* Quadrantid meteor shower peaks on the 4th

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Venus – Venus is the brilliant beacon in the southwest after sunset. As bright as Venus is it will only get brighter and higher in the sky for the remainder of the winter and into the spring. This year’s evening apparition is as good as it gets with peak visibility in March/April. The real showstopper occurs at the end of the apparition in June when Venus will transit the disk of the Sun. 2012 marks the last Venus transit till 2117. The Moon pairs up with Venus on the evenings of 25th and 26th.

Jupiter -  The King of Planets shares the evening sky with Venus. It is high in the southeast sky at the end of evening twilight. Past its late October opposition occurred it will slowly fade from magnitude -2.6 to -2.3. This month it resumes moving prograde through the constellation of Aries. Not that you’ll need the Moon to find Jupiter but the two will make a nice pair on the nights of the 1st-3rd and 29th-30th.

Morning Planets

Mars - With opposition in March 2012, Mars double in brightness (magnitude +0.2 to -0.5) as it begins to retrograde near the Leo-Virgo border. Mars rises around 11 pm on the 1st and 9 pm on the 31st. The Moon pairs up with Mars on the mornings of the 12th and 13th.

Saturn - Saturn rises 3 hours after Mars. At magnitude +0.7 Saturn will be located ~6-7° to the lower right of the slightly fainter star Spica in Virgo (magnitude +1.0). The Moon visits on the morning of the 16th.

Mercury – Mercury starts off the new year at  the tail end of a rather good morning apparition. By mid-month it has sunk back into the glow of dawn.

Meteors

Meteor activity starts off high at the beginning of the month but then drops quickly as the month prgresses. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During January mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Quadrantids (QUA)[Max Date = Jan 4, Max ZHR = ~60-200 per hour]

The Quadrantids are the best shower that you’ve probably never heard of. It’s bad enough that this shower peaks in the middle of winter in the northern hemisphere, but it is also named after a long defunct constellation. When first identified in the early 1800s, the meteors were observed to radiate from the small faint constellation of Quadrans Muralis (the Mural Quadrant). Unfortunately, the constellation didn’t make the cut when the official list of 80 constellations was set in 1930. Today, Quadrans Muralis and the radiant of the Quadrantids can be found on the northern reaches of the constellation Bootes.

Another strike against observing the Quadrantids is their short duration. Most showers, like the Perseids and Orionids, produce high rates of meteors for a few days near their maximum. The Quadrantids are only highly active for 12-24 hours. As a result, the shower can be missed if the peak does not coincide with your early morning observing.

The peak time for this shower is always uncertain on the order of half a day or so and the IMO prediction calls for a peak at 7:20 UT on Jan 4 though this time could be off be 12 hours or more. Observers in Europe and the Americas will be well placed for seeing this year’s peak. Unfortunately observers south of the Equator will not see much from the Quadrantids.

Back in 2009 this shower put on a great show with the peak well observed from the US. Peak rates that year reached a ZHR of ~150-160. But in 2008 and 2011, rates “only” reached into the 80s. The Moon will be a problem until it sets around 3 am. Then again the radiant only gets high enough for easy observing after 3 am so the Moon is not much of a problem.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

C/2011 W3 (Lovejoy)

The Surprise Comet of 2011 proved the experts wrong and became the most spectacular comet since Comet C/2006 P1 (McNaught) in 2007. Terry Lovejoy is no stranger to new comets and C/2011 W3 marks his 3rd comet discovery. The Australian amateur used an 8″ telescope and CCD camera to first spot the comet on November 27. Though a diffuse relatively faint 11-12th magnitude object at discovery it was rapidly approaching the Sun. In fact, Comet Lovejoy is a member of the Kreutz sungrazing family of comets which can pass extremely close to the Sun. A small number of Kreutz sungrazers have been seen from the ground over the past 1000 years and a few have ranked as some of the best comets of all time (1106, 1843, 1880, 1882, 1887, 1965). The last Kreutz to be seen from the ground was Comet White-Ortiz-Bolelli in 1970. Since then over 2000 faint “pygmy” sungrazers have been observed close to the Sun by Sun-watching spacecraft.

Based on the apparent faintness of C/Lovejoy as it approached perihelion on December 16 at a distance of only 87,000 miles (140,000 km), it was not expected to survive long past perihelion. Surprisingly the comet did survive after showing some odd behavior near the Sun (comet appeared to fade at perihelion only to rebrighten hours later also it appeared to loss its tail until a new one formed). Due to the orientation of its orbit relative to Earth, the comet is currently only observable from the Southern Hemisphere. A number of southern observers were able to see the comet as a brilliant long tailed object of negative magnitude. Even now the tail is being reported between 20 and 40° in length. The head has rapidly faded suggesting the nucleus has either decreased greatly in activity or even broken up.

Racing away from the Sun the comet will travel across a large swatch of the southern sky this month. For northern observers we may have a chance to see what’s left of Lovejoy towards the end of the month as the comet moves north through the dim constellations of Pictor and Caelum.

Here’s Comet Lovejoy in all its glory as seen from the International Space Station and imaged by astronaut Dan Burbank.

Comet Lovejoy is visible near Earth's horizon in this nighttime image photographed by NASA astronaut Dan Burbank, Expedition 30 commander, onboard the International Space Station on Dec. 22, 2011. Credit: NASA/Dan Burbank.

Additional photos of Comet Lovejoy can be found at the sites of Seiichi Yoshida, Astronomical Society of Victoria, and Cometography (Gary Kronk).

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

Until the arrival of Comet Lovejoy, Comet C/2009 P1 (Garradd) held the title of brightest comet of 2011.  First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion occured 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and is already a borderline naked eye object for observers at very dark sites. I was able to observe the comet on the morning of January 2, 2012 with 10×50 binoculars and estimated its brightness at magnitude 6.7.

The comet starts the month at a distance of 1.56 AU from the Sun and 1.94 AU from Earth. At mid-month it is 1.58 AU from the Sun and 1.76 AU from Earth and by month’s end it will be 1.64 and 1.56 AU from the Sun and Earth, respectively.  Though the comet is post-perihelion and moving away from the Sun, it is also moving closer to Earth. As a result, the comet should brighten a little more this month.

Traveling north to the left of the ‘keyhole’ of Hercules, Comet Garradd is an early morning object this month.

Date       RA       DEC     Delta    r    Elong   Mag
Jan 1    17h 30m  +26°50'   1.936  1.555    53    6.6
Jan 16   17h 27m  +32°23'   1.762  1.584    63    6.5
Jan 30   17h 18m  +40°37'   1.561  1.638    76    6.4

Small Telescope Comets (V = 8.0 – 10.0)

None

2011 October Monthly Highlights

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2011.

October 2011 Highlights
* Draconid meteor shower may produce high rates over Europe and Asia on the 8th
* Jupiter is at opposition on the 28th
* Comet C/2009 P1 (Garradd) is a nice binocular object during the evening
* Orionid meteor shower peaks on the 21st

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Mercury – Mercury spends the later half of the month in a poor evening apparition. Usually such a poor apparition wouldn’t be worth observing but this month Venus can be used to find Mercury. Use the Moon to find low but brilliant (magnitude -3.9) Venus and even lower and fainter (magnitude -0.3) Mercury on the evenings of October 27 and 28.

Venus – After spending the past month or so too close to the Sun to be observed, Venus is now starting its slow crawl into the evening sky. Its elongation from the Sun grows from 13° to 20° in October. Still you will need a clear view of horizon to catch Venus low in the WSW during early twilight. Use the Moon to find low but brilliant (magnitude -3.9) Venus and even lower and  fainter (magnitude -0.3) Mercury on the evenings of October 27 and 28.

Jupiter -  The King of Planets is the King of the Night Sky this month. With the other 4 naked eye planets hugging the twilight horizon or rather faint, Jupiter is by far the brightest and best placed. Rising a little over an hour after sunset on the 1st and right at sunset on the 31st, it is at its best around midnight. Opposition occurs on October 28 when Jupiter will peak in brightness at a magnitude of -2.9. For the entire month it will be slowly retrograding in the constellation of Aries. Not that you’ll need the Moon to find Jupiter but the two will make a nice pair on the nights of the 12th and 13th.

Morning Planets

Mars - With opposition in March 2012, Mars continues to slowly brighten (magnitude +1.3 to +1.1) as it moved from Cancer into Leo this month. Mars rises after midnight and is best just before dawn. If you are out watching the Orionids, Mars will be the bright ruddy star near the Moon on the mornings of the 19th and 20th.

Saturn - Saturn passes conjunction on the far side of the Sun at mid-month (Oct 13). Those with very clear eastern horizons may be able to see Saturn an hour before sunrise by the end of the month. Saturn (magnitude +0.7) will be located ~5° to the lower right of the slightly fainter star Spica (magnitude +1.0).

Meteors

Meteor activity is still near a seasonal high in October. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During October mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky. The Taurids should also contribute another 2-5 meteors per hour all night long.

Major Meteor Showers

Draconids (Giacobinids) (GIA) [Max Date = Oct 8, Max ZHR = highly uncertain between 50 and 600 per hour]

On October 8th at ~20 hours UT, the Draconid meteor shower may produce an outburst of meteors for observers in Europe and Asia. While normally a weak shower, the Draconids put on two of history’s best meteor storms in 1933 and 1946. In those years rates as high as 10,000 per hour were seen. More recently an outburst in 1998 produced a few hundred meteors per hour. This year the Earth will cross dust trails produced by Comet 21P/Giacobini-Zinner in 1900 and 1907, the same two trails that produced the 1933 and 1946 storms, as well as older trails back to 1866. Due to the older age and dispersion of these streams, a major storm is not possible this year. Still ZHRs as high as a few hundred per hour may be possible. The actual number of meteors seen by observers will be much less due to the nearly Full Moon. As a result, the shower may “only” appear as good as the Perseids or Geminids at their peak under a Moon-less sky.

If you’re like me and live in North America, well, we are probably out of luck. Chances are we will see little or no enhancement from the dust trail crossings. This will probably only be a good show for those in Europe, Asia and northern Africa. A map of visibility and much more information on this year’s shower cab be found at the International Meteor Organization’s (IMO) 2011 Draconids site.

Orionids (ORI) [Max Date = Oct 21, Max ZHR = ~35-45 per hour]

The Orionids are one of the most reliable and productive showers of the year. Another point in their favor is their high level of activity over the course of ~5 nights or so. This gives ample opportunity to catch a few Orionid meteors. This year the just past Third Quarter Moon will hamper meteor watching somewhat.

The meteors that make up the Orionid shower were originally released by the one comet everyone has heard of, Comet Halley. Computer simulations of the past movements of Halley and its dust suggest that many of this year’s Orionid meteors were released by Halley between 1265 BC and 910 BC (for some points of reference, the Trojan War took place around 1200 BC and King David ruled around 1000 BC).

The Orionids are usually active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. During their peak, rates can be as high as 20-70 meteors per hour. During the last two years ZHRs reached 35-45 meteors per hour which is nearly half the rate observed in 2007 (70 per hour). This year’s activity should be similar to the last few years. With a Moon-lit sky, actual rates will be somewhat lower.

The Orionids appear to come from an area in northern Orion. This area, called the radiant, rises around 10pm local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 1am). The radiant is highest around 3:30am which is the best time to look. As you can see on the sky chart, the Moon is almost on top of the radiant. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2011 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

The brightest comet of the year is long-period comet C/2009 P1 (Garradd). First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion will occur 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and is already a borderline naked eye object for observers at very dark sites (6th magnitude).

The comet starts the month at a distance of 1.92 AU from the Sun and 1.70 AU from Earth. At mid-month it is 1.81 AU from the Sun and 1.87 AU from Earth and by month’s end it will be 1.72 and 2.01 AU from the Sun and Earth, respectively.  Visual observers are placing the comet at magnitude 6.6 to 6.8 at the end of September. It should slightly brighten this month as it slowly moves west in Hercules.

Date       RA       DEC     Delta    r    Elong   Mag
Oct 1    18h 09m  +19°23'   1.697  1.921    87    6.7
Oct 16   17h 49m  +18°51'   1.866  1.811    71    6.6
Oct 31   17h 37m  +18°44'   2.005  1.716    59    6.6

Small Telescope Comets (V = 8.0 – 10.0)

45P/Honda-Mrkos-Pajdusakova

First seen in 1948 by Japanese amateur Minora Honda, Czech astronomer Antonin Mrkos and Slovak astronomer Ludmilla Pajdusakova, this comet is on its 11th observed return since discovery (it was missed during the 1959 and 1985 returns). It is an intrinsically faint Jupiter-family comet which passes within 0.53 AU of the Sun every 5.25 years. This time perihelion passage occurred on September 28. Prior to perihelion the comet made a close approach to within 0.06 AU of Earth which was only easily visible from the Southern Hemisphere. During the next return in 2016/2017, 45P will pass within 0.08 AU of Earth on its outbound leg and will be much better placed for northern observers.

Being after perihelion, the comet will rapidly fade as it moves away from the Sun and Earth as it moves through the constellation of Leo. At the start of the month, it should still be a binocular comet at magnitude 7.6 but will be lost to binoculars within a week or so. At an elongation of 32-37° it can only be seen low on the horizon before dawn.

Date       RA       DEC     Delta    r    Elong   Mag
Oct 1    10h 26m  +08°27'   0.827  0.532    32    7.6
Oct 16   11h 17m  +05°26'   1.139  0.641    34    9.9
Oct 31   12h 03m  +01°40'   1.380  0.839    37   12.7

 

 

Leonids in 2009

Note: Most of this article was first posted a year ago. It has been updated to include predictions for this year’s Leonid display.

The Leonids are the meteor storm-producing shower against which all other showers are measured. In most years the Leonids are a rather minor shower producing up to 15 meteors per hour, but on occasion they can produce some of the most spectacular meteor displays ever seen.

Comet 55P/Tempel-Tuttle, The Leonid Parent Comet

The Leonids are the result of dust released by Comet Tempel-Tuttle. Similar to the stories of the discoveries of Comets Encke (parent of the Taurids) and Biela (parent of the Andromedids), Comet Tempel-Tuttle was observed a few times before its periodic nature was noted. The first sighting happened way back in 1366 when the comet was observed by Chinese astronomers. Though the Chinese reported very accurate positions of the comet, especially impressive in an age without telescopes, the science of computing comet orbits had not yet been invented. Hence, there was no way to for them to know if this comet could return.

Fast forwarding a little over 3 centuries, Gottfried Kirch of Guben, Germany, finds a new comet on the night of 1699 October 26. Unfortunately, the comet is no where to be found on later nights. We now know that this was Comet Tempel-Tuttle and it was moving to the south so rapidly that the comet was not observable from Germany on the nights after Kirch’s discovery.

The comet would have to wait another ~167 years before it was found again. This time two of the 19th centuries premiere comet hunters, Ernest W. L. Tempel (Marseille, France) and Horace P. Tuttle (Cambridge, MA), found the comet almost 3 weeks apart. Tempel found the comet first on the night of 1865 December 19. Since news traveled slow in those days, the comet was independently discovered by Tuttle on 1866 January 9 before the news of Tempel’s discovery reached America. Not only was the periodic nature of the comet recognized at that time but so was its association with the Leonid meteors.

The comet resides on an orbit that spans from just inside the orbit of the Earth (0.98 AU) to slightly beyond the orbit of Uranus (19.7 AU). It takes the comet ~33 years to orbit the Sun. The the comet last passed perihelion (closest distance to the Sun) in 1998 and was well observed at that time.

tempel_tuttle_outer
Orbit of Comet Tempel-Tuttle and the Leonid meteors. Orbit diagram produced with the C2A planetarium program (http://www.astrosurf.com/c2a/english/index.htm)

The Leonids Roar

leonids-18331
The most famous depiction of the 1833 meteor storm. It was actually produced in 1889 for the Adventist book ‘Bible Readings for the Home Circle’ based on a first-person account of the 1833 storm by minister Joseph Harvey Waggoner on his way from Florida to New Orleans.

The first recorded appearance of the Leonids was in 902 AD when the shower was seen from Italy and Egypt. For the next few centuries, impressive Leonid displays were observed every 33 to 200 years or so.

Two Leonid storms stand out from all the others. On 1833 November 13, the entire eastern United States was awaken to a sight very few had every seen. The sky appeared to be filled with meteors. Modern researchers now know the cause of this outburst. It is estimated that a rate of up to ~70,000 meteors per hour was observed. That works out to ~20 meteor per second.

The 1833 storm marks the dawning of the modern age of meteor science. It was due to observations of this storm that astronomers first recognized that meteors originate in space. About 30 years later, after the discovery of Comets Swift-Tuttle (parent of the Perseids) and Tempel-Tuttle (the parent of the Leonids), the connection between comets and meteor showers was made.

The 1833 storm ranks as one of the 2 best meteor displays in recorded history. 133 years after the 1833 storm, the Leonids once again set the skies ablaze. On the night of 1966 November 17, the western United States experienced a storm just as strong as the 1833 storm.

When the comet returned in 1998, there were many predictions for spectacular Leonid activity. Though meteor rates never got close to that seen in 1833 or 1966, rates as high as a few thousand meteors per hour were observed in multiple years. The best meteor shower I have ever seen was the 1998 Leonid fireball display. Though I would observe Leonid displays with much higher rates of meteors, the sheer number of extremely bright meteors in 1998 was breathtaking.

Predictions for the 2009 Leonids

Now that it is over 11 years since the perihelion of Comet Tempel-Tuttle, what can we expect. In most years when the comet is not in the vicinity of Earth (which is true this year), the Leonids are a nice but relatively light shower with rates up to 15 meteors per hour.

This year the peak is predicted for the morning of November 17. But there are predictions by a number of different research teams for enhanced activity this year. The International Meteor Organization summarizes this year’s prediction with the following taken from their 2008 Meteor Calendar:

This year may produce another enhanced return of the Leonid meteor shower, with ZHR hourly rates expected to exceed 150+ according to independent studies by Jérémie Vaubaillon, Mikhail Maslov, Esko Lyytinen (WGN), David Asher, Mikiya Sato and their respective collaborators. The main peak(s) are expected to occur in the night of November 17 to 18 around 22h00 UT (= 17h00 US Eastern, 23h00 Central Europe, 3h30 India, 6h00 Beijing), although variable activity may happen at almost any stage between November 16 and 18. Continuous monitoring is necessary. Leonids are generally only visible after local midnight from any longitude, with the exception of some long Earth-grazing Leonids before midnight when the radiant is still very low.

What does this mean? Most of us, especially in the United States, will only see the “normal” maximum on the mornings of November 17 and 18 with rates on the order of 20-50 per hour. Observers in the Far East and central Asia may see rates as high as 100-200 per hour on the morning of November 17. The following times may see enhanced activity as the Earth encounters dense dust trails created by Comet Tempel-Tuttle during some of its past perihelion passages. Note, the times are for the predicted peak in activity. The dust trails are wide so expect enhanced activity for a few hours before and after the predicted peak times.

YYYY-MM-DD  HH:MM   Trail  Rev  Rates
             (UT)   Year
2009-11-17  07:27   1567   13     25
2009-11-17  21:43   1466   16    115
2009-11-17  21:50   1533   14     80
2009-11-18  03:29   1102   27  10-50

YYYY-MM-DD - Year, Month and Day of trail encounter in UT
HH:MM - Hour and minute of trail encounter in UT
Trail Year - Year the trail was created by Comet Tempel-Tuttle
Rev - Number of orbits trail has completed
Rates - Possible meteor rates per hour (this is on top of the background rate 10-30 per hour)

The International Meteor Organization has a “live” graph of reported Leonid activity at their website.

The best way to see the Leonids is to find the darkest site possible. Even if you are in brightly lit area, some Leonids will be observable. The Leonids, like many meteor showers, are only observable after midnight. You will not see any Leonids in the evening. The best time is from 2am till the start of dawn. The meteors will appear to radiate from the east from a spot in the constellation of Leo. Leonids are very fast and each individual meteor will only last for less than a second. Some of the Leonids may be bright and they often leave behind faint glowing trails that can last from a second to many minutes after the meteor occurred.

As for the future, we may have seen the end of the great Leonid storms. The orbits of the Leonids and Comet Tempel-Tuttle are slowly moving away from Earth due to the gravity of the planets. Though there may be Leonid displays with meteor rates as high as hundreds to a few thousand per hour around the time of Comet Tempel-Tuttle’s next perihelion in 2031, there will be no great storms. There is a possibility of one last hurrah for the Leonids around the time of its perihelion in 2131.

Nov 16/17 Meteors and the Peak of the Leonids

In yesterday’s “The November Meteor Storms – Part II – The Leonids” posting, it was mentioned that there were a few chances for elevated activity last night for Europe and Asia. Mikhail Maslov predicted a high rate of Leonids for an hour or so on either side of 00h 22m UT on November 17. Jérémie Vaubaillon also predicted elevated rates of Leonids centered at 01h 32m UT on November 17. According to Vaubaillon, the high rates would be due to the Earth crossing a trail of dust released by Comet Tempel-Tuttle in 1466.

According to the International Meteor Organization‘s Leonids 2008 Live webpage, a nice outburst of Leonids was observed at ~02h 00m UT on November 17. Based on the Leonids Live page and posts to the Meteorobs list at Yahoo Groups, observers in Europe and Israel witnessed the outburst. Rates may have reached as high as ZHR=~130.

By the time the Leonids were visible from the United States, the outburst was over. The 23 Leonids seen by my Tucson-based camera show that no outburst was visible over Tucson. Bob’s tally of 30 Leonids over San Diego also confirms this. Comparing video rates with naked eye observeing rates is tricky. Last month, when my camera detected roughly ~23 Orionids in a night, the visual observers were measuring ZHRs (zenithal hourly rate) of 10-20. So, with a bit of hand waving, the Leonids were falling at a ZHR of 10-20 over the western US last night. This is the expected rate for the Leonids when no elevated activity is seen. As you will see in Bob’s comments, his experience is that the Leonids will continue to strengthen till the morning of the 19th. So maybe there is more to come.

From Bob Lunsford’s notes: “The weather continues to cooperate in San Diego. I had the camera on from dusk to dawn and recorded 87 meteors. The first Leonid was recorded at 12:30 am PST and 29 more were caught the remainder of the night. That is an average of roughly 6 Leonids per hour. While Carl has mentioned the possibility of enhance rates may seen from the eastern hemisphere on the 17th, my personal data show that the strongest Leonid rates have been occurring on the morning of November 19th. We will have to see what actually happens.”

Jérémie Vaubaillon predicts the possibility of another period of elevated Leonid activity at 21:38 UT on November 18 though rates will may not be as high as those seen last night over Europe. This “outburst” will be observable over Asia.

Below are 2 movies from Tucson. The 1st shows the brightest Leonid (or meteor of any kind) observed by my Tucson-based camera last night. This doesn’t mean that there weren’t even brighter meteors observable over Tucson. My camera only covers a small fraction of the sky so I do miss a lot of meteors.

12421

The 2nd movie shows 47 of the meteors detected by my Tucson-based camera. The camera is fixed so you can easily see the stars and the Moon moving from East to West through the field. The big white blob moving along the bottom of the frame is the Moon.

leo5

Movie of 47 meteors (includind 23 Leonids) seen by the SALSA camera over Tucson on the night of November 16/17 MST. The big bright blob in the bottom of most frames is the Moon.

Obs  Date (UT)   TotTime TOT SPO NTA STA LEO AMO
TUS  2008-11-17  11h 33m  48  22  0   1   23  2
SDG  2008-11-17  11h 27m  87  45  6   5   30  1

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
NTA – Northern Taurids
STA – Southern Taurids
LEO – Leonids
AMO – Alpha Monocerotids

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