12/20/2017 – Ephemeris – All the visible bright planets are in the morning sky
Ephemeris for Wednesday, December 20th. The Sun will rise at 8:15. It’ll be up for 8 hours and 48 minutes, setting at 5:04. The Moon, 2 days past new, will set at 7:27 this evening.
Let’s take our weekly look at the bright planets. There are no bright planets visible in the evening sky now. While Uranus and Neptune are evening planets, they require binoculars or a telescope to spot. The morning sky is now host to three planets, though Venus, the brightest will rise too close to the Sun to spot. It’s way on the other side of the Sun, and it will pass behind the Sun in superior conjunction January 9th. At 7 this morning Mars is in the southeast while Jupiter is a lot brighter and below and left of it. Mars will rise tomorrow morning at 3:54. It’s approaching Jupiter which will rise 39 minutes later at 4:33. Tomorrow Saturn will be in conjunction with the Sun and will officially enter the morning sky. It will be a month or more before it separates far enough from the Sun to spot in morning twilight.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The only bright solar system object visible in the evening is the thin crescent Moon that will be exhibiting Earth shine this evening December 20, 2017. Created using Stellarium.
The bright morning planets visible at 7 a.m. this morning, December 20, 2017. Mercury is too close to the horizon to spot. Created using Stellarium.
Jupiter and its four Galilean moons as they might be seen in a telescope at 7 a.m. this morning, December 20, 2017. Created using Cartes du Ciel (Sky Charts).
Planets at sunset and sunrise of a single night starting with sunset on the right on December 20, 2017. The night ends on the left with sunrise on the 21st. Click on the image to enlarge. Created using my LookingUp program.
12/19/2017 – Ephemeris – Were celestial events in 7 BC interpreted as the Star of Bethlehem?
Ephemeris for Tuesday, December 19th. The Sun will rise at 8:15. It’ll be up for 8 hours and 49 minutes, setting at 5:04. The Moon, 1 day past new, will set at 6:34 this evening.
This year we have no bright evening Christmas star. But what about the one described in the Bible, in the gospel of Luke? We will look today at the first of two events that may have been recorded as the Star of Bethlehem. In 7 BC there was a rare event over 6 months when three times the planet Jupiter passed Saturn against the stars of the constellation Pisces. Could the Persian astrologer priests called Magi, have read into the event enough significance to start the journey to Jerusalem in search of the new born King of the Jews? It was the scribe’s readings that then sent them to Bethlehem. It is thought that Pisces was associated with the Hebrews, Jupiter with the Messiah or world ruler, and Saturn with the peoples of Palestine.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Jupiter-Saturn triple conjunction of 7 BC. Click on the image to enlarge. Created using Cartes du Ciel.
The animation above shows the planets at 5 day intervals in 7 and a bit in 6 BC. The normal or posigrade motion is toward the east or left. When an outer planet approaches its opposition from the Sun, it seems to slow and reverse direction and head westward for a time, which is retrograde motion. After a time it reverses and heads back eastward again. That’s why the planets seem to see-saw back and forth. Jupiter passes Saturn every 20 years. The next time will be in 2020. On my Wednesday planet charts Jupiter is seen sneaking up on Saturn week by week. In order to have three conjunctions instead of one, the planets need to be near opposition from the Sun when they pass. The last time that happened was in 1980, but it wasn’t against Pisces. Triple conjunctions against a particular zodiacal constellation are much rarer.
The dates for key events in the animation above are:
- First Conjunction May 29, 7 BC
- Planets are Stationary July 6, and begin retrograde motion
- Second Conjunction October 11
- Planets are Stationary November 1 and resume posigrade motion
- Third Conjunction on December 8
- Mars joins February 26, 6 BC
Retrograde motion was difficult to explain when one thinks that the Earth is the center of the Universe and stationary, while the planets supposedly orbited in perfect uniform circular motion around it. It’s easy when the Earth is a moving planet like the rest. When an outer (superior) planet is at opposition from the Sun. The Earth is between the Sun and planet and moving faster. So we’re passing the outer planet. When you are in a car passing another, the car being passed seems to move backward with respect to your car. Since the planets orbits are like a race track, we get to lap the outer planets at regular intervals.
12/18/2017 – Ephemeris – The little dog shall lead
Ephemeris for Monday, December 18th. The Sun will rise at 8:14. It’ll be up for 8 hours and 49 minutes, setting at 5:03. The Moon is new today, and won’t be visible.
The constellation Orion has two hunting dogs. At 9 p.m. we’ll see one of them, the lesser dog, Canis Minor whose bright star Procyon is low in the East. Just two stars mark the constellation. Is it a dachshund or maybe a hot dog? The name Procyon means “Before the dog”, an odd title. It means that though east of Sirius, the bright dog star in Orion’s large dog, Canis Major, it rises before Sirius, due to its more northerly position in the sky. At 9 Sirius is just rising in the east-southeast. In many ways Procyon is nearly a twin of Sirius. It shines with the same white color, although a bit cooler, and has a white dwarf companion like Sirius. It’s a bit farther away than Sirius’ 8.6 light years. Procyon is at a distance of 11.46 light years.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Stars and constellations in the east at 9 p.m., about 4 hours after sunset, on December 18th. This only works for locations above 30 degrees north latitude. Created using Stellarium.
12/15/2017 – Ephemeris – Taurus, Bullish on Winter
Note: The title of this post I’ve taken from an article I wrote for the December 1999 issue of the Stellar Sentinel, the monthly newsletter of the Grand Traverse Astronomical Society, which I will reprint with some tweaks, as the addendum to this post. Winter will arrive in six days, though I’m not particularly bullish on it, but it fits the constellation I’m talking about today.
Ephemeris for Friday, December 15th. 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 before new, will rise at 6:25 tomorrow morning.
Low in the east-southeast at 9 p.m. is the constellation of Orion the giant hunter. Above him is Taurus the bull. His face is a letter V shape of stars lying on its side with the bright orange-red star Aldebaran at the bottom tip of the V as its angry blood-shot eye. Orion is depicted in the sky facing him with club in one hand and a shield in the other the approaching and in some depictions charging Taurus. The V of stars is a star cluster called the Hyades. The Pleiades are in his shoulder above. Taurus, in Greek mythology, was the guise the god Zeus when he carried off the maiden Europa. Europa’s still with him, sort of, as the intriguing satellite with a buried ocean orbiting Zeus’ Roman equivalent the planet Jupiter.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Three views of Taurus the bull and Orion the hunter for about p.m. in December.
The Hyades (lower left) and the Pleiades (upper right). My photograph from many years ago BD (Before Digital).
The first constellation of winter to appear is probably a toss-up between Auriga the charioteer and Taurus the Bull. Auriga never quite disappears, or at least Capella its brightest star is circumpolar and never quite sets here in Northern Michigan. But Auriga sneaks up slowly in the northeast. Taurus on the other hand makes a grand entrance on autumn evenings preceded by the Pleiades, the Seven Sisters star cluster.
Taurus’ brightest star is Aldebaran, the bull’s angry bloodshot eye. It is at the left tip of a letter V of stars that is the bull’s face. Above the V are single stars that form the tips of its very long horns. Other stars below form the front legs of this beast. That’s it. Only the front part of the bull appears in the sky. In its shoulder are the Pleiades.
According to Greek mythology Taurus represents the god Zeus, the Roman Jupiter, who, in the disguise of a bull abducted the beautiful maiden Europa. This isn’t the only celestial disguise of Zeus. Cygnus is the disguise of Zeus in the famous Leda and the swan affair.
The Pleiades and the Hyades, the V-shaped star cluster of Taurus’ head also have their places in Greek Mythology. The Hyades and Pleiades are half sisters of each other who share Atlas as their father. But it is the Pleiades which are more prominent and have more stories about them. It is the Pleiades that are pursued by Orion the hunter, the central constellation of winter. And since the Pleiades are west of Orion it does appear that Orion continues to chase them around and around the sky daily. To the Kiowa Indians the Pleiades were also young maidens. As the story goes they were being chased by a large bear. The Great Spirit placed them on what we know today as Devil’s Tower in Wyoming to keep them out of reach of the bear. It is said that even today the sides of this tower show the scars of the bear’s claws. Devil’s Tower was the prominent landmark in the movie Close Encounters of the Third Kind. To the Anishinaabek native peoples around here the Pleiades is the “Hole in the Sky” or the seven sweating stones that are heated for the sweat lodge ceremony.
What do we know about Taurus today? Aldebaran is an orangish giant star which lies at a distance of 65 light years. It doesn’t belong to the Hyades, which is about 151 light years away. Aldebaran’s diameter is 40 times the Sun’s, about the diameter as the orbit of Mercury. It’s only 1.7 times tha mass of the Sun. Aldebaran shines at 153 times the Sun’s output.
Aldebaran appears to be part of the Hyades cluster, but it is less than half the distance to this most important star cluster. Though less prominent as the Pleiades, the Hyades is the most important star cluster in the heavens. The reason is because the Hyades was until recently the only star cluster close enough to get an accurate distance measurement by direct means. That direct means is parallax, measuring the shift of the star’s position in the sky due to the earth’s changing position in orbit of the Sun. The Hipparcos satellite has been refining these parallaxes over the past few years. Its measurement of the distance of the Hyades cluster is 151 light years give or take a bit less than a light year. The Hyades distance is the basis for all more distant measurements to the ends of the known universe.
The Hyades is a good binocular object with over 100 stars visible. The cluster actually overflows the binocular’s field of view. This cluster is also known as the Taurus Moving Cluster because its stars are receding towards a point northeast of Orion’s Betelgeuse.
Of course the splashiest part of Taurus is the Pleiades. For people with good vision 6 or more stars can be seen. I can see 4 or 5 stars and fuzz, which are unresolved stars. Many, who see the Pleiades for the first time, think the tiny pattern of stars is the Little Dipper. The stars do indeed look like a tiny dipper, with a nice bowl and a sawed off handle. And that’s what I call it: the Tiny Dipper. The big surprise of the Hipparcos distance measurements is the distance of the Pleiades. The generally accepted distance was about 410 light years. Hipparcos measured 375 light years. This means that the stars of the Pleiades are somewhat dimmer than believed before. Pleiades prior measurement was based on photometric or brightness measurements with the stars of the Hyades and other stars of the same type and known brightness and distance. So it turns out in the case of the Pleiades that the former measurements weren’t as accurate as thought, and means we have more to understand about stellar evolution as it relates to star brightness. Or perhaps Hipparcos is wrong. And interesting debate and more measurements are sure to follow.
The age of the Pleiades is thought to be around 100 million years, young compared to the Sun’s 4.6 billion years. Long exposure photographs and some telescopes can still spot the remaining wisp’s of the nebulae they were born from. The material is probably dust simply reflecting the light of the stars in the cluster.
Taurus is a great constellation to scan with a pair of binoculars.
12/14/2017 – Ephemeris – The Moon wanders over to Jupiter this morning
Dec 14. This is Bob Moler with Ephemeris for Thursday, December 14th. The Sun will rise at 8:11. It’ll be up for 8 hours and 50 minutes, setting at 5:02. The Moon, half way from last quarter to new, will rise at 5:26 tomorrow morning.
This morning the planet Jupiter will appear right below the crescent Moon. Jupiter is hard to miss, even without the Moon to point it out. It is with the rare exception of Mars when being its closest to the Earth the second brightest of the planets, after Venus. Speaking of Mars, which is to the upper right of Jupiter and has a reddish hue, if you’re going to send anything to Mars, next spring is the time to do it. Flight times to Mars are 6 to 7 months. The midpoint of the flight is when Mars is closest to the Earth, which next year is July 31st. NASA’s Insight Lander, grounded in 2016 due to an instrument failure has to wait 26 months for the next launch opportunity in May of next year.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon, Jupiter and Mars this morning, December 14, 2017. Earth shine should be visible as shown, though not as prominent. Created using Stellarium.
A Hohmann lowest energy transfer orbit to Mars. This diagram is for the Mars Exploration Rovers Spirit and Opportunity launched in 2003, arrived in 2004. Solid planets, Spirit launch and arrival. Ghost planets, Opportunity launch and arrival. Credit NASA/JPL.
What’s a Hohmann transfer orbit? NASA explains.
12/13/2017 – Ephemeris – The bright planets of morning
Ephemeris for Wednesday, December 13th. The Sun will rise at 8:11. It’ll be up for 8 hours and 51 minutes, setting at 5:02. The Moon, 3 days past last quarter, will rise at 4:26 tomorrow morning.
Let’s take our weekly look at the bright planets. We have no bright planets in the evening sky now. While Uranus and Neptune are evening planets, they require binoculars or a telescope to spot. The morning sky is now host to three planets, though Venus, the brightest will rise too close to the Sun to spot. It’s way on the other side of the Sun, and it will pass behind the Sun in superior conjunction January 6th. At 7 this morning Mars is below the crescent Moon in the southeast while Jupiter is a lot brighter and below and left of it. The Moon will be above it tomorrow morning. Mars will rise tomorrow morning at 3:58. Jupiter will rise an hour later at 4:54. Remember that the Geminid meteor shower will reach its peak tonight through tomorrow morning. It’s the best meteor shower of the year.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars, Jupiter and the Moon this morning at 7 a.m., December 13, 2017. Created using Stellarium.
The Moon as it might be seen in binoculars this morning at 7 a.m. December 13, 2017. Created using Stellarium.
Jupiter and its 4 Galilean moons as they might be seen in a telescope at 7 a.m. this morning, December 13, 2017. Created using Cartes du Ciel (Sky Charts).
Planets at sunset and sunrise of a single night starting with sunset on the right on December 13, 2017. The night ends on the left with sunrise on the 14th. Click on the image to enlarge. Created using my LookingUp program.
12/12/2017 – Ephemeris – The Geminids are coming!
Ephemeris for Tuesday, December 12th. The Sun will rise at 8:10. It’ll be up for 8 hours and 52 minutes, setting at 5:02. The Moon, 2 days past last quarter, will rise at 3:25 tomorrow morning.
Tomorrow evening through Thursday morning we will have the chance to see the peak of the Geminid meteor shower. Some of its members can be seen tonight, but the meteors will be most numerous on the morning of Thursday the 14th. This shower is currently besting the Perseid meteor shower of August with a predicted 120 meteors per hour Thursday morning. The problems for us in viewing this fabulous shower are the cold temperatures and usually cloudy skies. However the Moon won’t be a problem. The source of the Geminids was discovered in 1983. It is a burnt out comet with the asteroid designation 3200 Phaethon which swoops down to only 13 million miles of the Sun, but will is near Earth this time around. The Geminids were first seen in 1862
The times given 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.
This is an animation from two years ago, so ignore the planet positions. Times are in Universal time for the Grand Traverse Region and Eastern Time. So subtract 5 hours from UT. The sequence starts at 9 p.m. EST and ends at 6 a.m.
12/11/2017 – Ephemeris – Orion rising
Ephemeris for Monday, 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, 1 day past last quarter, will rise at 2:22 tomorrow morning.
Off in the east-southeast at 9 in the evening the great constellation of Orion will be seen. This is the most famous of all constellations world-wide. We think the Big Dipper is a big deal. It’s not even a constellation, being the hind end of the great bear Ursa Major. Also it’s invisible if one travels far enough south of the equator. Orion is now a rectangle of stars tilted to the left as he rises. With three stars in a straight line in the center, his belt. They are aligned nearly vertically. Orion is a giant hunter. The rectangle depicts his shoulders and knees. Among its other bright stars Orion contains two of the brightest. The upper left star is the famous red giant star Betelgeuse. The lower left star is the blue-white super giant Rigel.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Orion fully risen in the east-southeast a 9 p,m, approximately 4 hours after sunset, December 11. Created using Stellarium and GIMP.
Note to Blog readers
As you probably know these posts are transcripts of my Ephemeris program. The length of the program is exactly 59 seconds, and the first paragraph takes approximately 14 of those seconds. So I don’t have much time for the topic at hand. Therefore I dole out information in rather small spoonfuls. I’ll be revisiting Orion many times over the winter, talking about the other stars, and wonders found among its stars, also its mythology. If you can’t wait, type Orion in the search bar for all the past programs on Orion. Don’t be surprised that much of the programs don’t change much from year to year. I post the week’s worth of Ephemeris program MP3s on my monthly website http://ephemeris.bjmoler.org/ under the Audio link.
Sunday night and into the wee hours of Monday morning is the time I usually write and record the programs for Tuesday through the next Monday. Blog postings are prepared the night before the air date.
12/08/2017 – Ephemeris – The earliest sunset of the year is tomorrow night
Ephemeris for Friday, December 8th. The Sun will rise at 8:06. It’ll be up for 8 hours and 55 minutes, setting at 5:02. The Moon, 2 days before last quarter, will rise at 11:04 this evening.
In thirteen days we will have the shortest day in terms of daylight hours. But the change isn’t uniformly distributed in the morning and evening. Tomorrow evening we will have the earliest sunset. Sunset times have been within the same minute for the last few days and will continue for the next few. The latest sunrise will occur on January second. The reason is that the Sun is traveling faster eastward than average, so the Earth’s rotation takes a little longer each day to catch up with it. Near the solstice the Sun is at a higher latitude, where the longitude lines are closer together, also the Earth is nearing its closest to the Sun, so moves faster its orbit adding to the effect. The effect exists in June but isn’t as noticeable.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
I had more complete thoughts about earliest and latest sunrises and sunsets earlier this year: https://bobmoler.wordpress.com/2017/03/13/03132017-ephemeris-more-thoughts-about-yesterdays-time-change/. Check the addendum.
12/07/2017 – Ephemeris – The constellation of Auriga the Charioteer
Ephemeris for Thursday, December 7th. The Sun will rise at 8:05. It’ll be up for 8 hours and 56 minutes, setting at 5:02. The Moon, 3 days before last quarter, will rise at 9:54 this evening.
The constellation Auriga the charioteer is about two-thirds the way up the sky in the east at 9 p.m. It is a pentagon of stars, with the brilliant star Capella at the top corner. Capella represents a she goat he’s carrying. A narrow triangle of stars nearby Capella is her kids. The Kids is an informal constellation or asterism. Within and near that pentagon, binoculars and telescopes will find several star clusters, groups of hundreds of stars born in the clump we still see them in. These star clusters will appear as fuzzy spots in binoculars. One called M 38 is near the center of the pentagon, M 36 is to the east of it and M 37, is farther east yet. The M designations come from Charles Messier who two centuries ago ran into them while looking for comets.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Auriga finder chart for 9 p.m. December 7th. any year. Created using Stellarium and GIMP.
Auriga, showing, among other things the Messier star clusters M 36, M 37, and M 38. Created using Cartes du Ciel (Sky Charts).
Cr 62 is Collander 62, a real or accidental star cluster of 4 stars called Auriga’s Diamond. There’s an arc of stars just right of M 38 called the Cheshire Cat. You can find these on Phil Harringtons’s Binocular Universe on the Cloudy Night’s website: https://www.cloudynights.com/articles/cat/articles/new-articles-in-monthname/binocular-universe-aurigan-treasures-r2646
