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Posts Tagged ‘C/2021 A1’

12/10/2021 – Ephemeris – Our last look at Comet Leonard before it leaves forever*

December 10, 2021 Comments off

This is Ephemeris for Friday, December 10th. Today the Sun will be up for 8 hours and 52 minutes, setting at 5:02, and it will rise tomorrow at 8:10. The Moon, at first quarter today, will set at 12:25 tomorrow morning.

This is the day of the earliest sunset of the year. It doesn’t coincide with the shortest day because the Earth is moving faster in its orbit than average and getting ahead of its rotation a bit. Comet Leonard’s last appearance in the morning sky is tomorrow or Sunday before twilight overwhelms it. At 6:30 am it will be just a bit south of due east at azimuth 93 degrees and an altitude of 9 degrees, a bit less than the width of a fist held at arm’s length. When it gets into the evening sky, its track will take will be along the horizon from the southwest to the south. It will come very close to Venus, and I suspect that is what will alter its orbit slightly, so it will never return and end up becoming an interstellar comet.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

* After this weekend, the comet will enter the evening sky, but will hang quite low to the horizon in evening twilight as it passes Venus, heads southward and fades. It would best be viewed by observers in the Southern Hemisphere. It’s headed out of the solar system in a hyperbolic orbit.

Addendum

Comet Leonard 7 am, 12/11/21

Comet Leonard (C/2021 A1) finder chart for 7:00 am, December 11, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 22.1 million miles away, and will come within 21.7 million miles at its closest to us on the 12th. Created using Stellarium.

Comet Leonard (C/2021 A1) in the morning

Comet Leonard’s positions at 7:15 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for December 10th. The star field will be shifting to the upper right each morning at 7:15 from the December 10th date at 7:15. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. Created using Cartes du Ciel (Sky Charts).

12/09/2021 – Ephemeris – Comet Leonard and the Oort Cloud

December 9, 2021 Comments off

This is Ephemeris for Thursday, December 9th. Today the Sun will be up for 8 hours and 53 minutes, setting at 5:02, and it will rise tomorrow at 8:09. The Moon, 1 day before first quarter, will set at 11:14 this evening.

Comet Leonard will only be available to be spotted for the next two mornings. After that, it will be too close to the direction of the Sun to be spotted. It came in from hundreds of times the Earth’s distance from the Sun from a spherical area around the solar system call the Oort cloud. This area, proposed as a source of comets, was named after Dutch astronomer, Jan Oort, who hypothesized its existence. Near as we can tell, Comet Leonard had been falling toward the Sun for 40,000 years. Tomorrow morning the comet will be nearly 30 degrees below and a bit left of the bright star Arcturus from 6:00 to 7 am tomorrow morning. 30 degrees is three times the width of one’s fist held at arm’s length.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Comet Leonard 6 am 12-10-21

Comet Leonard (C/2021 A1) finder chart for 6:00 am, December 10, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 23.1 million miles away, and will come within 21.7 million miles at its closest to us on the 12th. Created using Stellarium.

Comet Leonard (C/2021 A1) in the morning

Comet Leonard’s positions at 7:15 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for December 10th. The star field will be shifting to the upper right each morning at 7:15 from the December 10th date at 7:15. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. The tails shown here simply show the direction of the tail, which will be very short, if visible at all visually. Created using Cartes du Ciel (Sky Charts).

12/07/2021 – Ephemeris – This is the best week to view Comet Leonard

December 7, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, December 7th. Today the Sun will be up for 8 hours and 55 minutes, setting at 5:02, and it will rise tomorrow at 8:07. The Moon, halfway from new to first quarter, will set at 8:43 this evening.

The evening sky between 5:45 and 7 pm will feature Venus, the crescent Moon, with dim Saturn above it and Jupiter all in the southwestern sky. Saturn will appear dim, only in the early part of that period, due to bright twilight. Saturn is about midway between Venus and Jupiter. In the morning sky, Comet Leonard continues to fall inward toward the Sun. It’s passing relatively close to the Earth, now about 29 million miles. It will pass its closest to on Sunday at about 21 million miles, at which time we’ll have a hard time spotting it in morning twilight. Comet Leonard will stay barely bright enough to spot in dark skies by really sharp-eyed observers without binoculars or a telescope. The rest of us will need optical aid.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Comet Leonard finder 12/08/21 6:30 am

Comet Leonard (C/2021 A1) finder chart for 6:30 am, December 8, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 26.7 million miles away, and will come within 21.7 million miles at its closest to us on the 12th. Created using Stellarium.

Comet Leonard (C/2021 A1) in the morning

Comet Leonard’s positions at 6:30 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for November 27th. The star field will be shifting to the upper right each morning at 6:30 from the November 27th date at 6:30. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. Created using Cartes du Ciel (Sky Charts). I’ve reversed the colors from previous printings of this image. Reprinted from my article in the Stellar Sentinel, the newsletter for the Grand Traverse Astronomical Society.

12/06/2021 – Ephemeris – A new comet is reaching naked-eye or binocular visibility

December 6, 2021 Comments off

This is Ephemeris for Monday, December 6th. Today the Sun will be up for 8 hours and 56 minutes, setting at 5:02, and it will rise tomorrow at 8:06. The Moon, 2 days past new, will set at 7:27 this evening.

Comet 2021 A1, is also known as Comet Leonard, for its discoverer Gregory J. Leonard of the Mount Lemmon Survey, near Tuscon, Arizona. When it was found, on January 3rd this year, it was farther from the Sun than Jupiter. January 3rd of next year, less than a month from now, it will pass its closest to the Sun at a distance of around 57 million miles from the Sun. This is after falling in toward the Sun for the last 40,000 years. It will pass close to Venus, and its orbit will be tweaked to escape the solar system to eventually head out among the stars. Tomorrow morning it will be 7 ½ degrees or 3 fingers below left of Arcturus, the brightest star in the east before 6:30. It’s 5th magnitude, but still requires binoculars for most folks to be able to spot.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Comet Leonard finder 12/07/21 6:30 am

Comet Leonard (C/2021 A1) finder chart for 6:30 am, December 7, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 29 million miles away, and will come within 22 million miles at its closest to us on the 12th. Created using Stellarium.

Comet Leonard (C/2021 A1) in the morning

Comet Leonard’s positions at 6:30 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for November 27th. The star field will be shifting to the upper right each morning at 6:30 from the November 27th date at 6:30. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. The comet tails shown show the direction of the tail, if visible, only. Created using Cartes du Ciel (Sky Charts). I’ve reversed the colors from previous printings of this image. Reprinted from my article in the Stellar Sentinel, the newsletter for the Grand Traverse Astronomical Society.

03/15/2021 – Ephemeris – Newly discovered comet may reach naked-eye brightness by December

March 15, 2021 Comments off

This is Ephemeris for Ides of March, Monday, March 15th. Today the Sun will be up for 11 hours and 54 minutes, setting at 7:49, and it will rise tomorrow at 7:52. The Moon, 2 days past new, will set at 10:12 this evening.

Now that daylight saving time is here all the times I give for sunrises and sunsets bump up at least an hour along with anything else the rises or sets. It’s lighter out in the evening now. The end of nautical twilight, by which time it’s dark enough to see most of the stars and constellations ends around 8:21 tonight, but that will continue to advance toward 11 pm by July. On to possibly happier news, a comet was discovered, and is called Comet 2021 A1 (Leonard). It could reach naked eye visibility and be brightest in mid-December. I mean could. Comets are unpredictable, and so is our weather that time of year. I’ll have more on Comet Leonard, its antics and more about comets in general as it heads in from the outer solar system during this year.

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

Addendum

Comet Leonard orbit

Comet C/2021 A1 (Leonard) orbit and position as of March 15, 2021. The vertical lines (I call them stilts) show the orbit’s position above or below the plane of the Earth’s orbit. It will reach its closest point to the Sun on January 3, 2022, just inside Venus’ orbit. Click on the image to enlarge. Credit NASA/JPL Small-Body Database Browser.