Archive
12/14/2018 – Ephemeris – Bright Comet Wirtanen will be easy to find this weekend
Ephemeris for Friday, December 14th. The Sun will rise at 8:12. It’ll be up for 8 hours and 50 minutes, setting at 5:02. The Moon, 1 day before first quarter, will set at 12:06 tomorrow morning.
This weekend is the best time to spot Comet Wirtanen. Not only is near its brightest, but it will be passing just to the left of the beautiful star cluster the Pleiades from below. Comet Wirtanen will appear as a fuzzy spot, possibly to the naked eye, but is best seen in binoculars. The near first quarter Moon will be a bother, and make the comet harder to spot. On the 12th the comet passed its closest to the Sun, called perihelion, about 4.6 million miles outside the Earth’s orbit. On the 16th, Sunday, it will pass closest to the Earth at 7.2 million miles, as the 10th closest comet passage in modern times. Wirtanen is a member of the Jupiter family of comets captured by and orbit maintained by the planet Jupiter.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet 46P/Wirtanen positions for the next week. Positions are marked with month-date and magnitude. The latest magnitude prediction for December 15th is 3.3, 5.5 magnitudes brighter than shown here. Star field position is for 9 p.m. on the 12th. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
12/12/2018 – Ephemeris – The bright planets and a comet this week
Ephemeris for Wednesday, December 12th. The Sun will rise at 8:10. It’ll be up for 8 hours and 51 minutes, setting at 5:02. The Moon, 3 days before first quarter, will set at 10:05 this evening.
Let’s look at the bright planets for tonight. In the evening sky we have Mars still visible, but Saturn is all but lost in the bright twilight, setting at 6:22 p.m. It will pass conjunction with the Sun on New Years day. Mars will be due south at 6:30 p.m., and it will set at 12:10 a.m. Mars is moving eastward, crossing the constellation of Aquarius until the 21st, when it enters Pisces. Comet Wirtanen is moving northward, to the right of the V of stars that’s the head of Taurus the bull, and should be an excellent binocular object. On the 15th and 16th it will pass to the left of the Pleiades or Seven Sisters. Venus, our brilliant morning star, will rise at 4:19 a.m. in the east-southeast. The elusive planet Mercury will be seen below and left of Venus after it rises at 6:20 a.m.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Planets and the Moon
Mars, and Saturn over a Lake Michigan horizon seen at 5:45 p.m. tonight December 12, 2018. Created using Stellarium.
The waxing crescent Moon as it should appear tonight in binoculars. Created using Stellarium.
Morning planets Venus and Mercury. Jupiter is rising. December 13, 2018, 7:15 a.m.. Created using Stellarium.
Telescopic view of Venus tomorrow morning December 13, 2018. Created using Stellarium.
Planets, two comets and the Moon at sunset and sunrise of a single night starting with sunset on the right on December 12, 2018. The night ends on the left with sunrise on the 13th. Click on the image to enlarge. Comet Wirtanen is very close to opposition and to the south, so it rises after sunset and sets before sunrise. Created using my LookingUp program.
Two comets
Comet C/2018 V1 (Machholz-Fijikawa-Iwamoto) in twilight starting tonight December 12, 2018. The comet won’t climb that dramatically at 6 p.m. on the rest of the nights because the stars in the field will set 4 minutes earlier each successive evening. The latest magnitude estimate of the comet on December 15 is 7.3, two magnitudes brighter than shown here. It is just about impossible to spot in twilight. Created using Cartes du Ciel (Sky Charts).
Comet 46P/Wirtanen positions for the next week. Positions are marked with month-date and magnitude. The latest magnitude prediction for December 15th is 3.3, 5.5 magnitudes brighter than shown here. Star field position is for 9 p.m. on the 12th. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
12/05/2018 – Ephemeris – The bright planets and a comet tonight
Wednesday, December 5th. The Sun will rise at 8:04. It’ll be up for 8 hours and 58 minutes, setting at 5:02. The Moon, 2 days before new, will rise at 7:08 tomorrow morning.
Let’s look at the bright planets for tonight. In the evening sky we have Mars, but are about to lose Saturn. Saturn will be briefly visible very low in the southwestern sky from about 5:45 p.m. until it sets at 6:46 p.m. Mars will be in the south as the skies darken tonight. Mars will be due south at 6:41 p.m., and it will set at 12:13 a.m. Mars is moving eastward, crossing the constellation of Aquarius until the 21st, then it enters Pisces. Comet Wirtanen is moving northward, below and right of the V of stars that’s the head of Taurus the bull, and should be an excellent binocular object. Venus, our brilliant morning star, will rise at 4:24 a.m. in the east-southeast. The blue-white star Spica is still off to the right and a bit above it. Mercury will rise at 6:31 a.m. and might be spotted after that. Jupiter is near the Moon tomorrow morning, rising at 7:24 only 40 minutes before the Sun.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
The planets
Mars, and Saturn seen at 5:45 p.m. tonight December 5, 2018. Created using Stellarium.
Morning planets Venus and Mercury. Jupiter is about to rise at 7:15 a.m. December 6, 2018. Created using Stellarium.
Telescopic view of Venus tomorrow morning December 6, 2018. Created using Stellarium.
Planets, one comet and the Moon at sunset and sunrise of a single night starting with sunset on the right on December 5, 2018. The night ends on the left with sunrise on the 6th. Click on the image to enlarge. Comet Wirtanen is very close to opposition and to the south, so it rises after sunset and sets before sunrise. Created using my LookingUp program.
Bright comets
Comet C/2018 V1 (Machholz-Fijikawa-Iwamoto) in twilight starting tonight November 28, 2018. The comet won’t climb that dramatically at 6 p.m. on the rest of the nights because the stars in the field will set 4 minutes earlier each successive evening. The latest magnitude estimate of the comet on December 8 is 5.9, two magnitudes brighter than shown here. Created using Cartes du Ciel (Sky Charts).
Comet 46P/Wirtanen positions for the next week. Positions are marked with month-date and magnitude. The latest magnitude prediction for December 1st is 3.7, 5.4 magnitudes brighter than shown here. The comet may make magnitude 3 by mid-December. Star field position is for 9 p.m. on the 28th. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
12/03/2018 – Ephemeris – Comet Wirtanen should be bright enough for the naked eye or binoculars this month
Ephemeris for Monday, December 3rd. The Sun will rise at 8:02. It’ll be up for 9 hours and 1 minute, setting at 5:03. The Moon, half way from last quarter to new, will rise at 4:56 tomorrow morning.
Beside Comet Machholz-Fujikawa-Iwamoto which I talked about last Thursday and should be at peak brightness about now in the western twilit sky, we have another comet, this one Comet 46P/Wirtanen is brightening in the east in the evening. Wirtanen is a member of the Jupiter family of comets, whose 5.44 year orbit of the Sun takes it from just outside the Earth’s orbit to just inside Jupiter’s orbit. This time around it will come as close as 7.1 million miles of the Earth. As of Thanksgiving the comet was 100 times brighter than its nominal expected brightness. I don’t know if it will stay that way. It has a history of outbursts. If it keeps it up Wirtanen could be as bright as the Pleiades stars when it passes them on the 16th.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The path of Comet 46P/Wirtanen from November 21, 2018, to January 1, 2019. The labels are month, date, and expected magnitude. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
Check back every Wednesday at least where Comet Wirtanen will be past of the planet report. I’ll be covering the comet on other days throughout the month. Also check Seiichi Yoshida’s Weekly Information about Bright Comets: http://www.aerith.net/comet/weekly/current.html
11/29/2018 – Ephemeris – A potentially bright comet was discovered earlier this month
Ephemeris for Thursday, November 29th. The Sun will rise at 7:57. It’ll be up for 9 hours and 6 minutes, setting at 5:04. The Moon, at last quarter today, will rise at 12:17 tomorrow morning.
Three amateur astronomers Don Machholz of the US and by Shigehisa Fujikawa and Masayuki Iwamoto of Japan independently discovered a comet November 7th that bears their names. Now through next week or so ,it will be visible in the western sky in evening twilight. The comet has been rapidly brightening, much more rapidly than expected. It could theoretically be bright enough to spot with the naked eye by Sunday or Monday, but it must compete with evening twilight low in the western to southwestern sky. Comets are unpredictable in their brightness and appearance. As David Levy of Comet Shoemaker-Levy 9 fame once said: “Cats and comets have tails and do exactly what they want”. Check here for updates.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
11/28/2018 – Ephemeris – Bright planets and comets tonight
Ephemeris for Wednesday, November 28th. The Sun will rise at 7:56. It’ll be up for 9 hours and 8 minutes, setting at 5:04. The Moon, 1 day before last quarter, will rise at 11:05 this evening.
Let’s look at the bright planets for tonight. Two of them are visible in the evening sky. Saturn will be briefly visible very low in the southwestern sky and from about 6 p.m. and will set at 7:10 p.m. Mars will be in the south as the skies darken tonight. Mars will be due south at 6:52 p.m., and it will set at 12:17 a.m. Mars is moving eastward, crossing the constellation of Aquarius this month. It’s currently about midway through Aquarius, moving eastward and northward, so its setting time won’t change much over this month. Venus, our brilliant morning star, will rise at 4:33 a.m. in the east southeast. The blue-white star Spica is still to the right and a bit above it. There are two comets entering our sky. More on that tomorrow.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Planets and the Moon
Bright comets
11/25/2018 – Ephemeris Extra – Comet 46P/Wirtanen may be naked eye in December
Comet 46P/Wirtanen will be well placed in the evening sky for observation. Though a small comet, it has a history of being active, which is not disappointing us now. It will be closest to the Earth on December16th at 7.1 million miles (11.4 million km).
On December 16th the comet will be closest to the Pleiades. On the 23rd it will appear close to the bright star Capella. After that it will become circumpolar.
Comet Wirtanen is a small short period comet of 5.44 years. It’s orbit doesn’t come as close to the Sun as the Earth. It’s closest to the Sun, called perihelion it which it reaches December 12th is about 98 million miles (158 million km). The orbit extends out to nearly Jupiter’s orbit.
Checkout photos and animations of this and other comets in http://www.spaceweather.com/’s Realtime Comet Gallery.
Also check out Seiichi Yoshida’s website and his weekly information about Bright Comets: http://www.aerith.net/comet/weekly/current.html.
A note about comet magnitudes
Comet magnitudes are always devilishly hard to estimate. A comet always appears dimmer than its magnitude suggests because one is comparing the brightness of a diffuse object with the point source of a star. One either has to reduce the size of the comet to almost a point or defocus the star to the size of the comet to make the comparison if it doesn’t have a tail.
A point about magnitudes. They’re like golf scores. The lower the number, the brighter the object, and the better the golf score. Blame the ancient Greek astronomer Hipparchus, who ranked star brightness from first magnitude for the brightest stars to sixth magnitude for the dimmest stars visible to the naked eye. Modern astronomers put a mathematical basis for the system saying that a magnitude difference of 5 equals a brightness difference of 100. So each magnitude step equals the 5th root of 100 or 2.512. So a 5thmagnitude star is about two and a half times brighter than a 6thmagnitude star, and so on.
