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10/06/2020 – Ephemeris – Mars is closest today, also the Draconid meteors are at peak

October 6, 2020 Comments off

This is Ephemeris for Tuesday, October 6th. Today the Sun will be up for 11 hours and 25 minutes, setting at 7:13, and it will rise tomorrow at 7:48. The Moon, 3 days before last quarter, will rise at 9:46 this evening.

Today Mars is at its closest to the Earth of this close approach, what astronomers call an apparition. The last close approach was at the end of July two years ago. It is still pretty small in telescopes. However being this close, 38.6 million miles (62.1 million kilometers) away, it is actually slightly brighter than Jupiter. Check them out. Mars is the bright orange tinged star in the east while Jupiter is in the south-southwest at 9 pm tonight. It’s still a week before Mars lines up with the Earth and Sun in opposition. Mars is closer now because it is moving away from the Sun in its orbit. We are at the peak of a weak meteor shower most years. It’s the Draconids, which appear to come from the head of Draco the dragon near the bright star Vega, nearly overhead in the evening.

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

Addenda

Mars

Inner solar system on October 6, 2020 showing Mars at it’s closest to the Earth. Note the motion of the planets and space probes are counterclockwise. Mars is moving away from its closest point to the Sun at about the 2 o’clock point in its orbit. Note that at this time Mars, the Earth and Sun are not yet in line, so Mars isn’t directly opposite the Sun from the Earth, called opposition. That will occur on the 13th. The Mars 2020 Rover “Percy” has a bit more than 4 months to go to reach Mars. Credit: NASA Eyes App https://eyes.nasa.gov/

Draconid Meteor Shower

The Draconid radiant in the head of Draco. Looking high in the northwest at 9 pm October 6th. The source of the Draconids is the Comet 21P/Giacobini-Zinner. The stars of the Summer Triangle are named.

Comet Giacobini-Zinner was the third comet I had ever seen. It was through my newly completed 8″ reflector in 1959, when the comet was quite close to the Earth. The comet just skims the Earth’s orbit at its perihelion, so the Earth passes through its trail of debris each year at this time. The meteor shower is very weak, 5-10 meteors an hour, unless the comet is near to the Earth at the time, as it was in 2018. The comet has an orbital period of about 6.6 years, so this year’s peak isn’t supposed to be the best. However this year me might have two mini peaks tonight in the 9 to 10 pm hour as the Earth is expected to pass through two old meteoroid trails. according to the International Meteor Organization’s 2020 Meteor Shower Calendar we are expected to pass through the 1704 trail at 9:25 pm, EDT and the 1711 trail at 9:57 pm EDT. This is October 7th at 1:25 UT and 1:57 UT. The normal projected peak is October 8 at 12:30 UT, that’s Thursday at 8:30 am, after sunrise.

04/30/2020 – Ephemeris – See bits of Halley’s Comet in the morning crashing into the Earth’s atmosphere

April 30, 2020 Comments off

This is Bob Moler with Ephemeris for Thursday, April 30th. Today the Sun will be up for 14 hours and 13 minutes, setting at 8:47, and it will rise tomorrow at 6:32. The Moon, at first quarter today, will set at 3:47 tomorrow morning.

Do you remember seeing Halley’s Comet back in 1986? The actual pronunciation is “Hawley’s”, according to Sir Edmund’s contemporary Samuel Pepys. The reason I asked is whether you saw it in 1986 or are young enough to live long enough to see it in 41 years, we all have a twice yearly chance to see bits of Halley’s Comet, shed in previous returns through the inner solar system and strewn along its orbit, burn up in Earth’s atmosphere as the Eta Aquariid meteor shower going on now, or the Orionids in late October. The time to see the meteor shower is in the early morning after the Moon sets. That’s after 3:47 a.m. tomorrow morning and 4:22 Saturday morning. Astronomical twilight starts about 4:40 a.m. It will probably be 5 a.m. before it really interferes. With the meteors all over the sky, coming from the southeast.

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

Addendum

Eta Aquarid radiant

The Eta Aquariid radiant at the peak of the shower. The radiant moves slowly to the east with time. Credit: my LookingUp program.

Halley's Comet Orbit and meteor showers

Halley’s Comet orbit with the orbits of the inner planets showing the points at which the debris from the comet intersect with the Earth’s orbit causing meteor showers. Diagram credit JPL Small-Body Database Browser with my annotations.

12/13/2019 – Ephemeris – Tonight is the first night that straddles the peak of the Geminid meteor shower

December 13, 2019 Comments off

Ephemeris for Friday, December 13th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:02, and it will rise tomorrow at 8:12. The Moon, 1 day past full, will rise at 6:33 this evening.

Tonight and tomorrow nights will straddle the peak of the Geminid meteor shower. It is the best meteor shower of the year and it is getting more active over the years. The Moon will interfere with all but the brightest meteors. The radiant is the point in space where the meteors seem to come from, which is near the star Castor in the constellation Gemini from which the shower gets its name. The meteors will be seen all over the sky, but they all can be traced back to the radiant. The body responsible for this meteor shower is an asteroid rather than a comet with the name 3200 Phaethon. It comes very close to the sun, So it may shed bits of itself due to heat stress. I suppose I can’t resist this: That’s how the asteroid crumbles.

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

Addendum

3200 Phaethon showing a tail

3200 Phaethon a rock comet showing a tail as it nears the Sun. Credit NASA/STEREO

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

The orbit of 3200 Phaethon

Orbit of 3200 Phaethon with the Earth and Phaethon at 10:02 p.m. December 12, 2019. (03:02 UT Dec 13) Credit TheSkyLive.com.

Geminid Orbits

Orbits of Fireballs on the night of December 13-14 as recorded by NASA’s All Sky Cameras six years ago. The preponderance of fireballs (bright meteors) are Geminids. These are published daily on Spaceweather.com. Credit: NASA and Spaceweather.com.

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

From the International Meteor Organization: Observing proposal: Geminids and Full Moon

 

12/12/2019 – Ephemeris – Previewing the Geminids this weekend

December 12, 2019 Comments off

Ephemeris for Thursday, December 12th. Today the Sun will be up for 8 hours and 51 minutes, setting at 5:02, and it will rise tomorrow at 8:11. The Moon, at full today, will rise at 5:38 this evening.

This upcoming weekend is the weekend of the greatest annual meteor shower of the year. They’re the Geminids. I confess to never having seen a Geminid. The reason is that it’s generally too cloudy, and for me too cold and this year is another problem, a bright Moon. In dark skies they have a 120 per hour peak, when the radiant point in Gemini is overhead. The body that was discovered to produce these meteors doesn’t appear to be a comet. It is designated as an asteroid 3200 Phaethon. Phaethon gets extremely close to the sun at 13 million miles (21 million km) and one of the STEREO Sun monitoring satellites caught it developing a tail when close to the Sun. Phaethon may then be the first known rock comet. I’ll have more on it tomorrow. (12/08/2014)

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

Addendum

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

Geminid Orbits

Orbits of Fireballs on the night of December 13-14 as recorded by NASA’s All Sky Cameras six years ago. The preponderance of fireballs in yellow (bright meteors) are Geminids. These are published daily on Spaceweather.com. Credit: NASA and Spaceweather.com

11/18/2019 – Ephemeris – More about the Leonid meteor shower that just reached peak this morning

November 18, 2019 Comments off

Ephemeris for Monday, November 18th. Today the Sun will be up for 9 hours and 28 minutes, setting at 5:12, and it will rise tomorrow at 7:44. The Moon, 1 day before last quarter, will rise at 10:56 this evening.

The Leonid meteor shower should have reached its peak early this morning hindered by a bright waning gibbous Moon. 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 55P/Comet Tempel-Tuttle, independently discovered by two astronomers Tempel and Tuttle in 1865 & 1866. The comet has 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

Leonid meteor shower as seen from space

The Leonid meteor shower as seen from space. The time is set for today so the Earth’s blue dot is lost in the stream of meteors crossing the Earth’s orbit (3rd one out from the Sun) just above the 9 o’clock position. The long ellipse is the orbit of Comet Tempel-Tuttle and the purple dot near the aphelion near Uranus’ orbit is the calculated current position of the comet. The flurry of dots are the calculated positions of meteors that whose orbits have been calculated. Click on the image to enlarge. Credit: NASA’s CAMS video camera surveillance network, and were calculated by meteor astronomer Peter Jenniskens of the SETI Institute and NASA Ames Research Center. This visualization is developed and hosted by Ian Webster.

These interactive animations can be found on the International Meteor Organization website:  https://www.imo.net. under Resources and Meteor Shower Calendar.

11/15/2019 – Ephemeris – The Leonids in the moonlight

November 15, 2019 Comments off

Ephemeris for Friday, November 15th. Today the Sun will be up for 9 hours and 35 minutes, setting at 5:14, and it will rise tomorrow at 7:40. The Moon, 3 days past full, will rise at 7:45 this evening.

We are coming into a period where the Leonid meteor shower will be at its peak, as the Earth passes through the debris left by Comet Tempel-Tuttle on past trips through the inner solar system. We are having a bright Moon now which will diminish their numbers. The Leonids are only visible after midnight, and that’s when the Moon is highest in the sky. 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. The Leonids are most numerous about every 33 years, which is about 13 years from now. Otherwise we get about 15 meteors an hour at peak when the Moon isn’t out.

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

Addendum

Leo rising at around 2 a.m. on the morning of November 20. Note the radiant .

Leo rising at around 2 a.m. on the morning of November 18. Note the radiant in the sickle asterism of Leo. Created using Looking Up, my own program.

New Meteor News!

I’ll have more next week, but we may be able to witness a meteor storm on the evening of the 21st and morning of the 22nd.  It is the Alpha Monocerotids.  They will seem to come from the constellation of Monoceros the unicorn.  That constellation lies in the blank spot in the triangle between Orion, Canis Major and Canis Minor.  The radiant will rise at 10:30 p.m.

Check this out:  https://www.syfy.com/syfywire/will-the-unicorn-give-us-a-meteor-storm-on-november-22

11/12/2019 – Ephemeris – November meteor showers

November 12, 2019 Comments off

Ephemeris for Tuesday, November 12th. Today the Sun will be up for 9 hours and 42 minutes, setting at 5:17, and it will rise tomorrow at 7:36. The Moon, at full today, will rise at 5:45 this evening.

November is a month with three meteor showers and all this year are affected by the bright moon, at least on the dates of their peak activity. They are the South Taurids which peaked last month but are seen through the 20th of this month; the North Taurids, which are at peak now, and whose members can be seen through December 10th; and the Leonids, which peak next Monday whose members can be seen until the end of the month. At peak on a dark night neither of these showers will produce more than 20 per hour. Both the Taurid meteor showers, which seem to emanate from the constellation of Taurus the Bull are related to Encke’s Comet the shortest periodic comet which orbits the Sun in only 3.3 years.

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

07/29/2019 – Ephemeris – The South Delta Aquariid meteor shower is at peak now

July 29, 2019 Comments off

Ephemeris for Monday, July 29th. Today the Sun will be up for 14 hours and 47 minutes, setting at 9:12, and it will rise tomorrow at 6:26. The Moon, 2 days before new, will rise at 4:30 tomorrow morning.

The South Delta Aquariid meteor shower is at its peak now. It’s not that great of a meteor shower. If its radiant were at the zenith we might expect 25 meteors an hour. The radiant will be highest low in the south at 3 a.m. However along with meteors appearing to radiate from the south from this meteor shower we expect growing numbers of meteors coming from the northeastern sky because the Perseid meteor shower that peaks around August 13th is beginning to be seen. The Perseids will be visible all night, but the South Delta Aquariids will be best seen after midnight. I suggest that you look for the Perseids before peak this year because the bright Moon will interfere at its peak.

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

Addendum

South Delta Aquariid meteor shower at peak and Perseids

South Delta Aquariid meteor shower at peak and Perseids firing up at 3 a.m. July 30 2019. PerR and DAqrR are the radiants.

05/06/2019 – Ephemeris – The Eta Aquariid meteor shower

May 6, 2019 Comments off

Ephemeris for Monday, May 6th. Today the Sun will be up for 14 hours and 27 minutes, setting at 8:53, and it will rise tomorrow at 6:24. The Moon, 2 days past new, will set at 10:52 this evening.

The Earth is now passing through a stream of bits of rock that were shed from Halley’s Comet on its many previous passes of the inner solar system. The Earth gets to pass through this stream twice, Once in late October as the stream passes the Earth’s orbit heading in, and in early May as the stream is departing. The peak of this meteor shower, the Eta Aquariids, lasts several days. But since the meteoroids are coming from nearer the direction of the Sun, there is only a short period when these meteors are visible. Actually only an hour between 3:30 a.m. and 4:30 a.m. or a little bit later in the Grand Traverse region as twilight begins to interfere with the display. The radiant, from where the meteors will seem to come will stay low in the east-southeast, but they will be seen all over the sky.  The farther south one is on the earth the longer each morning the meteors will be visible.  We’re at a disadvantage being 45º north latitude.

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

Addendum

Eta Aquarid Radiant

The sky at 4 a.m. tomorrow looking eastward at the Eta Aquariid radiant. Click on the image to enlarge. Created using Stellarium.

 

05/06/2019 – Ephemeris Extra – The Eta Aquariids – Halley’s Comet never really left

May 5, 2019 Comments off

In 1986 Halley’s Comet swam through our skies for the 28th time since the Chinese first recorded it in 240 BCE. It was not especially impressive, considering the week when my family met a group of Leelanau School students in the Florida Keys the week in April 1986 to view and photograph the comet at it’s closest to the Earth of 44 million miles. It turned out that that week the comet lost its tail, probably due to a coronal mass ejection from the Sun. Halley’s Comet was much more impressive a month later. I’ve seen more impressive comets before and since.

Comet Halley's path thru the inner solar sstem

Comet Halley’s path through the inner solar system in 1985-86. Created using my LookingUp program.

Halley’s Comet has been swinging around the Sun countless times before the Chinese first recorded it. The illustration above shows the last time the comet entered the inner solar system in 1986. The comet’s path is from upper right to lower left. When the comet passes within about 3 astronomical units of the Sun, that is 3 times the Earth’s distance from the Sun, the ices in the comet begin to sublimate, escaping from the comet’s nucleus which liberates dust and larger solid material. The gasses and dust form the comet’s ion and dust tails. The larger material, gravel sized bits, end up in and around the comet’s orbit, and over time are spread out around and near the comet’s orbit. Halley’s orbit crosses the Earth’s orbit twice, inbound and outbound. In both cases these crossings are close enough to the plane of the Earth’s orbit to produce meteor showers.

On the inboard leg of the orbit it produces the Orionid meteor shower that peaks on October 22nd. A meteor shower is generally named for the point in the sky they seem to come from, be it a constellation or star. The point, called the radiant, moves during the days or weeks the shower is visible. The Orionids are named for the constellation Orion. The radiant is near his upraised arm.

The center of the outbound meteoroid stream crosses the Earth’s orbit where the Earth is on May 6th. Though they have a broad peak of about 5 days. This meteor shower is visible from April 19th to May28th. During that period the radiant points drifts quite a bit to the east. There are several meteor shower radiants in Aquarius, so they are named for the nearest star at peak.

Motion of Eta Aquariid Radiant

Motion of the Eta Aquariid radiant from April 20 to May 25. The triangle with the star near the center near May 05 is the asterism the Water Jar, a part of Aquarius. Eta Aquarii is the triangle star to the left. Source: PDF version of the International Meteor Organization 2019 Meteor Shower Calendar: https://www.imo.net/resources/calendar/

Though the Moon is new for this shower, the meteoroids are coming from near the direction of the Sun, so there is only an hour where the Eta Aquariids are best seen. For Northern Michigan the radiant rises at 3:30 a.m. on May 6th. Astronomical twilight begins at 4:30 a.m. when the sky begins to brighten. This meteor shower is best seen from the southern hemisphere.