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11/19/2018 – Ephemeris – The Leonids’ comet 55P/Tempel-Tuttle

November 19, 2018 Leave a comment

Ephemeris for Monday, November 19th. The Sun will rise at 7:45. It’ll be up for 9 hours and 25 minutes, setting at 5:10. The Moon, half way from first quarter to full, will set at 4:29 tomorrow morning.

We have another day in this year’s extended Leonid meteor peak. In past years, usually every 33 years the Leonid meteors have a super peak, called a meteor storm, where thousands of meteors streak through the skies. These appear for a brief period over a rather small geographic area. In 1966 it occurred principally over the Rocky Mountains. The comet responsible is Comet Tempel Tuttle, independently discovered by two astronomers Tempel and Tuttle in 1865 & 1866. The comet had a 33 year orbit of the Sun, and its orbit crosses very close to the Earth’s orbit. Comets are notorious litter bugs, shedding gas, dust and pebble sized debris as they come close to the warming rays of the Sun.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Entire orbit of Comet Tempel-Tuttle
Entire orbit of Comet Tempel-Tuttle projected on the plane of the Earth’s orbit.. Credit C2A Planetarium program, copied from TransientSky.com
The comet's orbit and debris stream
The comet’s orbit and debris stream where it intersects the Earth’s orbit. Credit Katie Peek, Popular Science.
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11/16/2018 – Ephemeris – The Leonid meteor shower will have several peaks in the next few days

November 16, 2018 Leave a comment

Ephemeris for Friday, November 16th. The Sun will rise at 7:41. It’ll be up for 9 hours and 32 minutes, setting at 5:13. The Moon, 1 day past first quarter, will set at 1:19 tomorrow morning.

We are coming into an extended period where the Leonid meteor shower will be at its peak, or rather there is a chance of up to maybe four peaks as the Earth passes through the debris left by Comet Tempel-Tuttle on past trips through the inner solar system. We are having a pretty bright Moon now, but the best displays of the meteors are going to be occurring in the early morning hours after the Moon sets. The meteors will appear to come from the top of a backward question mark that is the head of the constellation Leo the lion. They will be seen all over the sky, but can be traced back to that point, if it’s a Leonid meteor. The Leonids are most numerous about every 33 years, which is about 15 years from now. Otherwise we get about 15 meteors an hour at peak.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Leonid radiant
The constellation of Leo the lion and the Leonid radiant for about 5 a.m.  Click on image to enlarge.  Created using Stellarium.

11/06/2018 – Ephemeris – The Taurid meteor showers

November 6, 2018 Comments off

Ephemeris for Election Day, Tuesday, November 6th. The Sun will rise at 7:27. It’ll be up for 9 hours and 57 minutes, setting at 5:24. The Moon, 1 day before new, will rise at 7:09 tomorrow morning.

We are in the midst of two showers of meteors that seen to come from the constellation of Taurus the bull. These are the Southern and Northern Taurids respectively. They only produce a handful of meteors per hour, but there seems to be some discrepancy in their peak dates. The International Meteor Organization has the Southern group peak October 10th. Other sources have it peak November 5th. The Northern group peaks on the 10th or 12th of November depending on the source. Anyway these are bits shed by Comet 2P/Encke, which has only a 3 year orbit of the Sun. Encke’s orbit also comes close to the Earth’s orbit where the Earth is at the end of June. I’ve always wondered if it was a piece of Encke’s nucleus that hit Siberia on June 30, 1908?

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Taurid Radiants at midnight in early November
The Southern and Northern Taurid meteor shower radiants at around midnight in early November. Created using Stellarium.

The radiants are not as nearly defined as shown here

10/18/2018 – Ephemeris – Halley’s Comet returns as the Orionids

October 18, 2018 Comments off

Ephemeris for Thursday, October 18th. The Sun will rise at 8:02. It’ll be up for 10 hours and 50 minutes, setting at 6:53. The Moon, 2 days past first quarter, will set at 2:32 tomorrow morning.

Halley’s Comet is back! (Pronounced Hall-ee’s) Well sorta. In the form of the Orionid meteor shower. Bits of Halley’s Comet from previous passes by the Earth’s orbit make their twice-yearly show in our skies as these bits collide with the Earth’s atmosphere. Halley’s orbit passes close to the earth’s orbit at points where the Earth is around May 6th and again near October 21st. Light dust and ionized gas get blown back into the tail of the comet. Heavier particles, still affected by the pressure of sunlight and the gravitational pull of the Sun and planets end up roughly following the comet’s orbit. In the morning after the Moon sets should be the best time to see them. They will seem to come from a spot above Orion and below Gemini.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Halley's meteor shower
We get two meteor showers from Halley’s Comet. The Orionids, when Halley is approaching the inner solar system, and the Eta Aquariids when it’s leaving. Credit my LookingUp program.

Orionid radiant
The Orionid Radiant is high in the south at 5 a.m. this weekend. Created using Stellarium.

08/09/2018 – Ephemeris – How to observe the Perseid Meteor Shower

August 9, 2018 Comments off

Ephemeris for Thursday, August 9th. The Sun rises at 6:38. It’ll be up for 14 hours and 19 minutes, setting at 8:57. The Moon, 2 days before new, will rise at 5:30 tomorrow morning.

Now through most of this month and reaching peak numbers Sunday evening and Monday morning the Perseid meteors will be shooting through our skies. Where to look? Up is the direction. All over the sky. They will seem to come from the northeast on parallel paths, like driving through a snow storm at night, the snowflakes will diverge from right in front of you. The numbers will generally increase as that radiant point rises higher in the sky. A diligent experienced, and undistracted, observer may see up to 100 or more an hour. Casual observers will see much less. The longest meteor streaks will be seen early in the evening when the meteoroids enter the atmosphere at 37 miles (59 km) per second at a very shallow angle, so last a bit longer.  Bring a blanket, dress warmly and enjoy the show!

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Perseid Sky Dome Animation

The sky dome for the night of the Perseid shower maximum at 1 hour intervals from 10:30 p.m. to 4:30 a.m. Click on image to enlarge. Created using my LookingUp program and GIMP.

For locations other than the Traverse City/Interlochen area the 10:30 step is approximately an hour and a half after sunset.

My best Perseid photo. From the 70's.

My best Perseid photo. From the 70’s.

Perseid Meteors

Here are some meteors seen in the 2007 Perseid meteor shower taken by Scott Anttila. The image is centered on Cassiopeia. The radiant is low and a bit left of center in the image. The Double Cluster is seen below center and the Great Andromeda Galaxy is seen on the right just above center.

The logic of taking meteor photos pointing near the radiant is the he meteors appear to travel slower there because they are coming mostly toward the camera and have a better chance of being picked up.  My photograph was unguided, so the stars trailed.  Scott’s was guided.

 

08/07/2018 – Ephemeris – The source of the Perseids

August 7, 2018 Comments off

Ephemeris for Tuesday, August 7th. The Sun rises at 6:35. It’ll be up for 14 hours and 24 minutes, setting at 9:00. The Moon, 3 days past last quarter, will rise at 3:18 tomorrow morning.

The Perseid meteor shower will reach its peak Sunday night and Monday morning, less than a week from now. The meteor shower is caused by tiny particles shed by the comet 109P/Swift-Tuttle on past trips through the inner solar system. The 109P means it was recognized as the 109th comet to have seen to return to the vicinity of the Sun to be rediscovered in 1992. Lewis Swift and Horace Tuttle first discovered the comet independently in 1862. The orbit of the comet fit the orbits of the meteoroids that produce the Perseid meteor shower each year. The comet will return in 2126 after retreating to 51 times the Earth’s distance from the Sun, deep in the Kuiper belt, leaving behind a trail of meteoroids.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Swift-Tuttle 1992 plot

The passage of 109P/Comet Swift-Tuttle through the inner solar system November 1, 1992 to January 30, 1993. The meteoroids shed by the comet on its numerous trips close to the Sun lie close to that orbit. Note that its orbit intersects with the Earth’s orbit. That’s where the Earth will be around August 12-13 every year. Click on the image to enlarge. Created using my LookingUp program.

08/06/2018 – Ephemeris – The meteors of August, the Perseids are showing up now

August 6, 2018 Comments off

Ephemeris for Monday, August 6th. The Sun rises at 6:34. It’ll be up for 14 hours and 27 minutes, setting at 9:01. The Moon, 2 days past last quarter, will rise at 2:27 tomorrow morning.

Over the past several weeks folks outdoors at night might have been seeing some shooting stars or meteors appearing to zip past in the sky. The ones I’m talking about seem to come from the northeast. These are the precursors of the Perseid meteor shower which will reach its peak on the night of August 12 and 13 this year. Over the millennia the meteoroid stream that feeds the meteors to our skies has spread out to last over a month from the latter half of July to three-quarters of August. We’ll meet the culprit for this show tomorrow. I try to use the proper terminology for all this. Meteoroid is the tiny body in space. In the Perseid’s case the size of a grain of sand to a pea. Meteor is the streak we see in the sky as it burns up.  Meteorite is the body that makes it to the ground.  To my knowledge no Perseid meteoroid has made it that far.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Perseid radiant

The Perseid radiant at 11 p.m. tonight, August 6, 2018. Note that the radiant position is different from what I show on my charts for the month. The radiant there is for the night of the Maximum, August 12th. The radiant point shifts with time due to Earth’s changing position with the meteoroid stream. Click on image to enlarge. Created using Stellarium.