Archive
12/22/2015 – Ephemeris – Welcome to winter, or summer if you’re down under
Ephemeris for Tuesday, December 22nd. The Sun will rise at 8:17. It’ll be up for 8 hours and 48 minutes, setting at 5:05. The Moon, 3 days before full, will set at 5:59 tomorrow morning.
Today is the first full day of winter. For folks south of the equator this is the first full day of summer. The Earth reached a point in its orbit where its north pole is tipped its furthest away from the Sun, and is in shadow in the middle of it’s six month night. We do see the Sun, though less than 9 hours of daylight, and to boot the Sun only rises 22 degrees above the horizon giving us the least amount of energy of any day of the year. Why did the ancients celebrate this time of year? That’s because the Sun had slowed and stopped its drift southward and was beginning to come back higher in the sky. They still had to go through the worst of winter, but the Sun was coming back. Spring and summer would eventually return!
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comparing the sun’s path at the summer and winter solstices. This is a stereographic representation of the whole sky which distorts the sky and magnifies the size of the sun’s path near the horizon.
The above chart shows the diurnal path of the Sun at the winter and summer solstices for Traverse City, MI near 45º north latitude. Peak Sun altitude at noon at the winter solstice is 22º, while it’s 69º at the summer solstice.
12/21/2015 – Ephemeris – Except for 12 minutes today is the last day of autumn.
Ephemeris for Monday, December 21st. The Sun will rise at 8:16. It’ll be up for 8 hours and 48 minutes, setting at 5:04. The Moon, 3 days past first quarter, will set at 4:50 tomorrow morning.
Here we are at the mostly last day of autumn. The last 12 minutes will be the start of winter. The winter solstice will occur at 11:48 this evening, here in the Eastern Standard Time Zone. Next year winter will start 18 hours earlier. The reason is that next year is a leap year and the addition of an extra day will push all the solstices and equinoxes back by about 18 hours. Why only 18 hours? 18 hours is three-quarters of a day, and by this time next year we will have used up a quarter of that adjustment already. The Earth takes approximately 365 and a quarter days to orbit the Sun, so a day is added every 4th year, except century years not divisible by 400. I’ll discuss more about the implications of the solstice tomorrow.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Not quite the solstice, this is the Earth on December 16th, 2015 taken by the EPIC camera on the DISCOVR spacecraft at the Sun-Earth L1 point, some 1.5 million miles (1 million km) from the Earth. Credit: NOAA.
12/18/2015 – Ephemeris – The Moon at first quarter tonight
Ephemeris for Friday, December 18th. The Sun will rise at 8:15. It’ll be up for 8 hours and 48 minutes, setting at 5:03. The Moon, at first quarter today, will set at 1:17 tomorrow morning.
By the time we see the moon tonight it will be at least 8 hours since the Moon passed the first quarter point and it’s terminator or sunrise line will appear slightly bowed. This time, since I can only point out a few features at a time, I’d like to point out three craters on the upper, north portion of the moon. They may be too small for binoculars, but fine for small telescopes. They make a nearly right triangle in Mare Imbrium, the Sea of Showers near the terminator. The largest is Archimedes, named for the 3rd century BC Greek mathematician, and inventor. The northern crater is Aristillus, named after a 3rd century BC astronomer, The other crater is Autolycus, named for a 4th century BC Greek astronomer.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The first quarter Moon on December 18 at 9 p.m. EST. Highlighted are the trio of craters of which Archimedes is the largest. Created using Virtual Moon Atlas.
Other features visible are the crater Plato, the Alpine Valley, the crater Alphonsus, which I’ve covered in the past. Search on them for their location and more information.
12/17/2015 – Ephemeris – The bright star Aldebaran the “follower”
Ephemeris for Thursday, December 17th. The Sun will rise at 8:14. It’ll be up for 8 hours and 48 minutes, setting at 5:03. The Moon, 1 day before first quarter, will set at 12:07 tomorrow morning.
The central constellation of winter Orion, will be rising the east-southeast at 9 p.m. Above it is Taurus the bull. The bright orange star in Taurus is Aldebaran. Aldebaran appears at the lower left tip of a letter V group of stars that is the face of the bull. Aldebaran isn’t actually part of the group, called the Hyades star cluster. The cluster is about 151 light years away, while Aldebaran is 65. The star has an orange hue because its surface is cooler than the sun’s. However Aldebaran is 44 times larger in diameter, and shines 425 times brighter than the sun, if you include the infrared which our eyes can’t detect, or 150 times brighter in visible light. The name Aldebaran means “Follower” because it follows the Pleiades star cluster above through the night.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Aldebaran, the Hyades and Pleiades star clusters. Created using Stellarium.
Three views of Taurus the bull and Orion the hunter for 9 p.m. on December 8, 2015. Created using Stellarium and GIMP.
12/16/2015 – Ephemeris – The planet action is still in the morning
Ephemeris for Wednesday, December 16th. The Sun will rise at 8:13. It’ll be up for 8 hours and 49 minutes, setting at 5:02. The Moon, 2 days before first quarter, will set at 10:57 this evening.
Let’s check out the whereabouts of the bright naked eye planets. Mercury is becoming marginally visible very low in the southwest before it sets at 6 p.m. In the morning sky there are three bright planets. Jupiter will be the first to rise, at 12:15 a.m. in the east. Mars will rise next at 2:39 a.m. also in the east, followed by Venus at 4:41 a.m. in the east-southeast. Mars lies in line between Venus below and Jupiter above, almost halfway between the two. Don’t confuse Mars with the star Spica which is brighter and right below it. Saturn will rise at 6:54 a.m. in the east-southeast. Comet Catalina is a telescopic object about one and a half the width of a fist held at arm’s length above Venus and the same amount left of Mars.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon as it might look in binoculars at 8 p.m., December 16, 2015. Created using Stellarium.
The Morning planets at 7 a.m., December 17, 2015. Created using Stellarium.
Jupiter and moons in a telescope at 7 a.m. December 17, 2015. Created using Stellarium.
Venus as seen in a telescope as seen at the same magnification as Jupiter above, at 7 a,m. December 17, 2015. Created using Stellarium.
Comet Catalina and Mars for the next week. Note the magnitudes for the comet are about 1 magnitude too bright. It will take binoculars or a small telescope to spot the comet which will not show a tail visually. Created using Cartes du Ciel (Sky Charts).
This is a chart showing the sunrise and sunset skies for December 16, 2015 showing the location of the planets and the Moon at that time. Created using my LookingUp program. Click on the image to enlarge.
12/15/2015 – Ephemeris – Procyon the star that’s “Before the dog”
Ephemeris for Tuesday, December 15th. The Sun will rise at 8:13. It’ll be up for 8 hours and 49 minutes, setting at 5:02. The Moon, 3 days before first quarter, will set at 9:48 this evening.
Visible low in the east at 9:30 p.m. appears the star Procyon to its lower left is Sirius the brightest night-time star. Procyon is the bright star in the constellation Canis Minor, or lesser dog. I can find only one other star in Canis Minor. Perhaps it’s a hot dog. If Sirius, in Canis major is the Dog Star then Procyon should be the Little Dog Star. However Procyon is an interesting name. It means “Before the dog”, which is an allusion to the fact that Procyon, though east of Sirius actually rises before it. This is due to Procyon’s more northerly position. This effect doesn’t work south of the equator, however. Sirius will rise at about 9 tonight. Procyon is a star much like Sirius but is 32% farther away. It’s 11.4 to Sirius’ 8.6 light years away.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Procyon, Sirius and the stars of winter. Created using Stellarium
In the above chart, beside the constellation lines, we have the grid of right ascension, from lower left to upper right; and declination, from upper left to lower right. right ascension lines are like longitude on the Earth, while declination lines are latitude lines. They are tipped because I don’t live at either the equator or one of the poles. As the Earth rotates the Sun, stars and planets slide westward in the direction of the declination lines. Note that Sirius is closer to the horizon than Procyon. Also that Sirius is west of the 7 hour right ascension line. (Take my word for it.) Procyon is east of that line, thus Sirius is west of Procyon.
Other cool things can be seen in the chart. Note the declination line that touches the horizon at the east compass point and runs just above Orion’s belt. It is 0º declination, or the celestial equator. It extends to the west compass point on the western horizon. The Sun on the equinoxes will rise due east and set due west. The 6 hour right ascension line runs past Betelgeuse in Orion. At 23½º north declination, near Castor’s big toe in Gemini is where the Sun appears on the first day of summer, the summer solstice.
P.S. It was cloudy and rainy the last two days. Didn’t see a Geminid meteor again this year, keeping my record intact.
12/14/2015 – Ephemeris – The Geminids reach peak today – See ’em morning or evening
Ephemeris for Monday, 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, 3 days past new, will set at 8:42 this evening.
The Geminid meteor shower is ongoing right now. The peak is expected to be near 1 p.m. today. So the numbers seen this morning while it’s still dark should be about the same as will be seen this evening. Not peak numbers, but it should be a good show nonetheless if it’s clear tonight. The radiant is in the constellation of Gemini above Orion. The source of this shower is an asteroid rather than a comet. It may be a burnt out comet which lost all its frozen gasses. It has a definite highly elliptical orbit of a comet and comes very close to the Sun, where one of the STEREO Sun monitoring spacecraft saw it ejecting a cloud of dust. It may be classed as a rock comet for that reason, blurring the line between comets and asteroids.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
All Sky view one hour intervals for The Geminid meteor shower the night of December 13-14, 2015.. Note the radiant “GemR”. Created with my LookingUp program and GIMP.
A Geminid and the aurora borealis from Norway. Found this in a NASA blog (link below) uncredited). However I was able to find the credit: Image Credit & Copyright: Bjørnar G. Hansen.
The image above was also an Astronomy Picture of the Day. Here’s a link to the NASA blog dated December 9, 2015 about live tweeting the Geminids.
12/11/2015 – Ephemeris – The Geminid meteor shower will be cranking up this weekend
Ephemeris for Friday, December 11th. The Sun will rise at 8:09. It’ll be up for 8 hours and 52 minutes, setting at 5:02. The Moon is new today, and won’t be visible.
Over the weekend and through Monday night the Geminid Meteor shower will be seen. This shower is actually the bet of the year, with higher hourly counts of meteors than the more famous Perseid meteor shower of August. Around here the cold weather and the more than even chance that it will be cloudy have kept this astronomer from having seen even one. Maybe this year. The Geminids can be seen all night because the radiant point is in the northern sky, well north of the celestial equator at least. At 9 p.m. the constellation Gemini rises sideways with the namesake of the twins, the stars Castor and Pollux vertically aligned in the east with Castor on top. The closest to the peak numbers will be seen Monday early morning and Monday night.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
All Sky view one hour intervals for The Geminid meteor shower the night of December 13-14, 2015.. Note the radiant “GemR”. Created with my LookingUp program and GIMP.
Note the times are in Universal time conversion to local time.
UT EST 2 9 p.m. 3 10 p.m. 4 11 p.m. 5 12 m. 6 1 a.m. 7 2 a.m. 8 3 a.m. 9 4 a.m. 10 5 a.m. 11 6 a.m.
For locations other than EST Eastern Standard time (UT – 5 hours), just use EST as your local time. The latitude is set for near 45º north.
12/10/2015 – Ephemeris – What’s a charioteer doing holding goats?
Ephemeris for Thursday, December 10th. The Sun will rise at 8:08. It’ll be up for 8 hours and 53 minutes, setting at 5:02. The Moon, 1 day before new, will rise at 7:59 tomorrow morning.
Rising now more than half way up the sky in the east at 9 p.m. will be the bright star Capella and its pentagonal constellation Auriga the Charioteer. Auriga appears to be hunched down sideways in the sky in his chariot carrying 4 goats. Capella is the mother goat, and a slim triangle of stars near her are her kids. Perhaps the kids in the chariot were such a distraction that he crashed. So maybe the gods placed them in the sky as a warning. In fact that triangle is an asterism widely known as the Kids. The Milky Way runs through Auriga and it is the home of several star clusters that appear as fuzzy spots in binoculars. Capella for us in northern Michigan never sets. It is a winter star that can be seen year round. It’s disconcerting to spot it scraping the northern horizon in July.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Auriga and neighboring constellations for 9 p.m. December 10, 2015. Created using Stellarium and GIMP.
12/09/2015 – Ephemeris – The planet action is in the morning sky
Ephemeris for Wednesday, December 9th. The Sun will rise at 8:07. It’ll be up for 8 hours and 54 minutes, setting at 5:02. We’re at the time of the earliest sunset. The Moon, 2 days before new, will rise at 7:02 tomorrow morning.
Let’s check out the whereabouts of the bright naked eye planets. Saturn and Mercury are too close to the direction of the Sun to be seen now. In the morning sky there are three bright planets. Jupiter will be the first to rise, at 12:39 a.m. in the east. Mars will rise next at 2:47 a.m. in the east, followed by Venus at 4:28 a.m. also in the east. Mars lies in line between Venus below and Jupiter above, almost halfway between the two. Don’t confuse Mars with the star Spica which is brighter and closer to Venus. Comet Catalina will be about half the width of a fist held at arm’s length above and left of Venus and will slowly be moving farther above Venus as the days go by.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter, Mars and Venus appear with Comet Catalina in the southeast at 6 a.m., December 10, 2015. Comet Catalina is much fainter than shown and only sports a tail in photographs. Created using Stellarium.
Jupiter and moons in a telescope at 6 a.m. December 10, 2015. Created using Stellarium.
Venus as seen in a telescope as seen at the same magnification as Jupiter above, at 6 a,m. December 10, 2015. Created using Stellarium.
Comet Catalina and Venus for the next week. Note the magnitudes for the comet are about 2 magnitude too bright. It will take binoculars or a small telescope to spot the comet which will not show a tail visually. Created using Cartes du Ciel (Sky Charts).
This is a chart showing the sunrise and sunset skies for December 9, 2015 showing the location of the planets and the Moon at that time. Created using my LookingUp program. Click on the image to enlarge.
