03/24/2016 – Ephemeris – Why is this Sunday Easter?
Ephemeris for Thursday, March 24th. The Sun will rise at 7:37. It’ll be up for 12 hours and 23 minutes, setting at 8:01. The Moon, 1 day past full, will rise at 9:19 this evening.
This Sunday is Easter, only 5 days later than the earliest Easter can ever be. Yesterday’s full moon or the tabular date for it is called the Paschal Full Moon, an attempt for the Christian Church to match the solar Roman calendar to the Jewish lunar calendar in regards to the date of Passover. It doesn’t always work, especially when Easter turns out to be early as it is this year. The simple formula for western churches is the first Sunday after the first full moon after the vernal equinox which is defined as March 21st, no matter the date spring actually started, which was the 20th, this year. All this started to be counted using the Julian Calendar, which is 11 minutes longer than the seasonal or tropical year. We’ll see how that was corrected for tomorrow.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Jewish calendar does not have a relationship with the Gregorian Calendar, so Passover will drift later and later into spring over the years. The Jewish calendar does have a relation to the Julian Calendar in that 19 years equals 235 lunar months. This was probably discovered by the Babylonians but was popularized by the Athenian Menton in the 5th century BCE. It’s a way to relate the lunar calendar to the solar or seasonal calendar. We call it the Metonic cycle.
In a lunar calendar the months alternate between 29 and 30 days because the lunar month is 29.53 days. Also a 365.25 day year is 12.37 lunar months. The solution for all this is quite complex, with 12 common or 12 month years and 7 13 month great years to fit the 19 year cycle. It also means that the phases of the moon repeat on or near the same date at 19 year intervals. If you see a quantity called the Golden Number in almanacs, which happens to be 3 this year, that’s where we are (1-19) in the Metonic cycle. The Gregorian Calendar breaks this relationship. We’ll see how tomorrow.
03/23/2016 – Ephemeris – Another planet defects from the morning sky
Ephemeris for Wednesday, March 23rd. The Sun will rise at 7:39. It’ll be up for 12 hours and 20 minutes, setting at 7:59. The Moon, at full today, will rise at 8:21 this evening.
Let’s check out the whereabouts of the bright naked eye planets. Jupiter is up at sunset, and will pass due south, astronomers call it a transit, at 12:45 a.m., and will set at 7:15 a.m. It’s below the stars of Leo now. Binoculars can make out some of Jupiter’s moons, but a telescope is required to see Jupiter’s cloud formations. Mars will rise next at 1:12 a.m. in the east-southeast. It’s seen in western Scorpius now. Saturn will rise at 2:02 a.m. in the east-southeast. It’s above the stars of Scorpius, actually in Ophiuchus. Its rings are a telescopic treat. Venus will rise at 7:05 a.m. again in the east-southeast. Mercury will pass in superior conjunction, that is behind the Sun, this afternoon and enter the evening sky.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter with the moon and the bright stars of winter and spring at 10 p.m., March 23, 2016. Created using Stellarium.
Jupiter and its moons on an active night as the would appear at 10 p.m. March 23, 2016. The equatorial diameter of Jupiter is 44.1″. Created using Cartes du Ciel (Sky Charts).
Tonight’s satellite events
| Event | Date/Time EDT | Date/Time UT | ||
| Europa Occultation Starts | 23 | — | 23 | 22:17 |
| Ganymede Transit Starts | 23 | — | 23 | 22:19 |
| Io Transit Starts | 23 | — | 23 | 22:22 |
| Io Shadow Crossing Starts | 23 | — | 23 | 22:24 |
| Ganymede Shadow Crossing Starts | 23 | — | 23 | 23:46 |
| Io Transit Ends | 23 | 08:36 PM | 24 | 00:36 |
| Io Shadow Crossing Ends | 23 | 08:58 PM | 24 | 00:58 |
| Ganymede Transit Ends | 23 | 09:31 PM | 24 | 01:31 |
| Europa Eclipse Ends* | 23 | 09:45 PM | 24 | 01:45 |
| Ganymede Shadow Crossing Ends | 23 | 11:04 PM | 24 | 03:04 |
| * When Europa’s occultation ends it will still in Jupiter’s shadow and will enter sunlight a bit away from the planet.
Timings are from Project Pluto. |
||||
The Moon and the morning planets Mars and Saturn with the summer stars at 7 a.m. March 24, 2016. Created using Stellarium.
Mars as it would be seen in a large telescope at 6 a.m. March 24, 2016. Apparent diameter is 11.0″ One quarter of Jupiter’s apparent diameter. Created using Cartes du Ciel (Sky Charts).
Saturn and Titan at 6 a.m. March 24, 2016. The planet’s apparent diameter is 17.2″ and the rings span 40.0″. Created using Cartes du Ciel (Sky Charts).
Mercury approaching the Sun from the right for the days March 19-22, 2016. Credit SOHO/NASA/ESA.
This is a chart showing the sunrise and sunset skies for March 23, 2016 showing the location of the planets and the Moon at that time. Created using my LookingUp program.
03/22/2016 – Ephemeris – Really difficult lunar eclipse to spot at sunrise*
Ephemeris for Tuesday, March 22nd. The Sun will rise at 7:41. It’ll be up for 12 hours and 17 minutes, setting at 7:58. The Moon, 1 day before full, will set at 7:48 tomorrow morning.
The Paschal full moon is tomorrow morning. I’ll explain more about it on Thursday as we get closer to Easter this coming Sunday. However as the Moon sets for our region it will be in eclipse. It’s not a big deal partial or total lunar eclipse, but a penumbral eclipse, where the Moon slips into the Earth’s outer shadow, where the Sun’s light is partially cut off by increasing amounts from the edge of the penumbra to the totally blocked umbral shadow. As the Moon is setting tomorrow morning after 7:30 a.m., it may be showing a dusky lower left edge, the part of the Moon closest to the center of the Earth’s shadow. It might difficult to see the effect, though the bright skies may actually help by washing out the light of the Moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
* The eclipse, such as it is, will not be visible east of us around 86º west longitude, and be more visible west of us.
Addendum
How lunar eclipses occur. Credit NASA/Fred Espenak.
This eclipse, however the Moon will dip only into the outer penumbra.
The Eclipse diagram for the March 23, 2016 penumbral eclipse of the Moon. Credit Fred Espenak/NASA/GSFC.
Here’s a link to the original pdf of the image above.
Maximum eclipse will occur at 7:47 a.m. EDT (11:47 a.m. UT)
What the progress of the eclipse is like at 7:40 a.m. The sky will be bright because the Sun will be rising at that time. Created using Cartes du Ciel (Sky Charts).
03/21/2016 – Ephemeris – Two dim comets are making close passes of the Earth
Ephemeris for Monday, March 21st. The Sun will rise at 7:43. It’ll be up for 12 hours and 14 minutes, setting at 7:57. The Moon, 2 days before full, will set at 7:21 tomorrow morning.
Tomorrow Comet P/2016 BA14 (Pan-STARRS) will come it’s closest to the Earth at about 2.2 million miles (3.5 million km) or about 9 times the distance of the Moon away. It may not be a coincidence that another small comet 252P/LINEAR 12 in nearly the same orbit will be passing the Earth today at 3.3 million miles (5.3 million km). The Pan-STARRS comet will set a record as the third closest comet known to pass by the Earth. Many local folks saw the previous third closest comet, IRAS-Araki-Alcok from the Rogers Observatory back in 1983, when it passed 12.2 lunar distances from the Earth. Radio telescopes which use radar to probe both comets’ nuclei may give us a clue as to whether these two comets are chips off the same block so to speak.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
252P/LINEAR was expected to reach 8th magnitude, but has recently brightened to 5th magnitude, visible in binoculars. It’s currently too far south to be seen. On March 25th it will rises above our horizon as it passes the tail of Scorpius, heading north. Credit: Jean-Francois Soulier via Seiichi Yoshida’s web site.
P/2016 BA14 ( PanSTARRS ) was discovered two moths ago it is too faint to be seen in all but the largest amateur telescopes. It’s currently passing the head of the constellation Hydra toward the head of Leo. This is a negative image. The dot is the comet. Credit: Jean-Francois Soulier via Seiichi Yoshida’s web site.
Seiichi Yoshida’s Weekly Information about Bright Comets link.
03/18/2016 – Ephemeris – Spring comes this weekend!
Ephemeris for Friday, March 18th. The Sun will rise at 7:48. It’ll be up for 12 hours and 4 minutes, setting at 7:53. The Moon, 3 days past first quarter, will set at 5:48 tomorrow morning.
Sunday’s the day I’ve been waiting for. Maybe you feel that way too. Because at 12:31 a.m. EDT (4:31 a.m. UT) Sunday March 20th the season of spring will begin. It’s not that we’ve had a hard winter. As winters go this has been a mild one. The Grand Traverse Bay never froze over. My heating bill has been low. Of course we have a chance for another snow storm or two before May gets here. However at the top of the show notice we’re getting over 12 hours of sunlight even now. The sun will reach its peak altitude of about 45 degrees at local noon. Those at the Straits will have to wait only a few more days for he Sun to reach that altitude. The Sun is rapidly moving northward, and the daylight hours are increasing by about 3 minutes a day.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Getting close to the equinox. Earth image from NOAA DSCOVR satellite’s Epic camera in a halo orbit around the Earth-Sun Lagrangian point 1, a million miles Sunward of the Earth. Taken March 14, 2016.
The Sun’s path through the sky from due east to due west on the equinox day from Traverse City, MI. Created using my LookingUp program.
That’s not a pumpkin on the head of the motorcyclist. That’s the Sun rising as I’m traveling east on South Airport Road south of Traverse City Mi. on the autumnal equinox. This is the east-west section of the road. The Sun is rising over the hills some 6 miles to the east. Credit: Bob Moler.
Traverse City’s latitude is 1/3º south of 45º north latitude. The Suns are plotted at 15 minute intervals. Each day the Sun will rise higher and higher until the summer solstice when the Sun’s path in the sky looks like this:
The Sun’s path through the sky on the summer solstice day from Traverse City, MI. Created using my LookingUp program.
For those south of the equator, summer is ending and autumn is starting.
03/17/16 – Ephemeris – Why are there no green stars?
Ephemeris for St. Patrick’s Day, Thursday, March 17th. The Sun will rise at 7:50. It’ll be up for 12 hours and 1 minute, setting at 7:52. The Moon, 2 days past first quarter, will set at 5:10 tomorrow morning.
Today we celebrate the patron saint of the Emerald Isle. And green is the color of the day. When we look to the skies we don’t see a lot of green. Well, maybe in the Hubble Space Telescope’s false color photographs like the original Pillars of Creation, where green represents hydrogen, and in the northern lights. The colors we see in stars are red or orange if they are cooler than the Sun, yellow if they are the same temperature as the Sun, and white or bluish if hotter than the Sun. In the spectrum of light we can see, green is in the middle, between yellow and blue. As a matter of fact the Sun radiates its energy most heavily in the green. So if you got rid of those other colors the Sun itself would be green.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Star cluster showing star colors, probably enhanced. Source uncredited image from planetsforkids.org.
“Black body” Radiation Curves by temperatures. The Sun’s surface temperature is around 5800 Kelvin. Note the peak radiation besides increasing in amplitude slides from red to blue with increasing temperature.
Aurora looking north at 10/24/2011 at 10:52 p.m. The first color visible in an aurora or northern lights is green. More active aurorae give off other colors. Credit: Bob Moler.
Looking overhead in an active aurora, and the variety of colors, even green. Credit: Bob Moler.
Pillars of Creation in false color by the Hubble Telescope. Sometimes the colors are given to specific elemental emissions, of shifted because the colors represent radiation that is invisible to the human eye. Credit: NASA/ESA/HST.
03/16/2016 – Ephemeris – Jupiter is in the evening, the other bright planets are in the morning
Ephemeris for Wednesday, March 16th. The Sun will rise at 7:52. It’ll be up for 11 hours and 58 minutes, setting at 7:50. The Moon, 1 day past first quarter, will set at 4:26 tomorrow morning.
Let’s check out the whereabouts of the bright naked eye planets. Jupiter is up at sunset, and will pass due south, astronomers call it a transit, at 1:13 a.m., and will set at 7:44 a.m. It’s below the stars of Leo now. Binoculars can make out some of Jupiter’s moons, but a telescope is required to see Jupiter’s cloud formations. Mars will rise next at 1:29 a.m. in the east-southeast. It’s seen in western Scorpius now. Saturn will rise at 2:29 a.m. in the east-southeast. It’s above the stars of Scorpius, actually in Ophiuchus. Its rings are a telescopic treat. Venus will rise at 7:13 a.m. again in the east-southeast. Mercury is lost in the bright morning twilight and will pass behind the Sun in superior conjunction a week from now.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter and the Moon with the bright stars at 10 p.m. on March 16, 2016. Created using Stellarium.
The Moon as it might appear in binoculars at 10 p.m. on March 16, 2016. Created using Stellarium.
Jupiter and its moons as they would be seen in a telescope, at 10 p.m. March 16, 2016. Jupiter has an apparent diameter of 44.3″ Created using Stellarium.
The morning planets Mars, Saturn and Jupiter at 6:30 a.m. March 17, 2016. Created using Stellarium.
Mars as seen in a large telescope at high power. It’s only 10.0″ in diameter, about a quarter of Jupiter’s diameter. The long dark area near the bottom or south is Mare Cimmerium. The bright area above center is Elysium. Created using Cartes du Ciel (Sky Charts).
Saturn and its large satellite Titan and other moons as they should appear in a telescope in the morning of March 17, 2016. The planet is 17.0″ in diameter while the rings span 39.6″. Created using Stellarium.
This is a chart showing the sunrise and sunset skies for March 16, 2016 showing the location of the planets and the Moon at that time. Created using my LookingUp program.
Some of these images above are shown smaller than actual size. Image expansion lately hasn’t worked. If you are using Firefox, right-click on the image, and then click on View Image.
03/15/2016 – Ephemeris – Spotting the celestial Horse and Rider
Ephemeris for, the Ides of March, Tuesday, March 15th. The Sun will rise at 7:54. It’ll be up for 11 hours and 55 minutes, setting at 7:49. The Moon, at first quarter today, will set at 3:36 tomorrow morning.
In the handle of te Big Dipper rising high in the east northeast is an easily seen double star. It’s the star second from the end of the handle where it makes a bend. The bright star is Mizar. It has a dim companion star that folks with good eyesight can easily spot, named Alcor. The Arabs of old, before optometrists used the pair as an eye test. I would have failed. Even with my glasses on I can’t spot Alcor. I must resort to binoculars. The pair is known as the Horse and Rider, while the indigenous peoples of North America, see the stars of the handle of the Big Dipper not as the great Bear’s tail, but hunters following the bear. In this case Alcor is either a hunting dog, or a cooking pot to cook the bear in.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Big Dipper, part of Ursa Major the Great Bear, is poised on its handle in the northeast. Can you spot Alcor? Created using Stellarium.
A closeup view of Mizar and Alcor and a dimmer star that lies in the background. Created using Stellarium.
A telescope with low power will also split Mizar intro a bright and dim companion named Mizar A and Mizar B. By observing Mizar A, B and Alcor have determined that all three are binary. There’s six stars there.
3.1416 – 03/14/2016 – Ephemeris – When Jupiter hits your eye like a big pizza Pi
Ephemeris for Pi Day 3/14, Monday, March 14th. The Sun will rise at 7:56. It’ll be up for 11 hours and 52 minutes, setting at 7:48. The Moon, 1 day before first quarter, will set at 2:39 tomorrow morning.
We turn again to the giant planet Jupiter which is shining brightly in the southeastern part of the sky in the early evening. The first thing one notices in a small telescope are it’s four moons, generally in a straight line, which move back and forth each night. Notice their plane. It’s the same direction as the cloud bands are aligned. Jupiter has a very small axial tilt, and its large satellites orbit pretty much over Jupiter’s equator. Our Moon doesn’t behave that way, but that’s another story. Jupiter rotates on its axis in a bit less than 10 hours, which whips its clouds into alternating bands of reddish-brown and cream color. Also the rotation rate of these clouds lessens with increasing latitude.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Transits of Europa and Io across the face of Jupiter at 11 p.m. EDT March 14, 2016. The shadows of the moons are hard to see, but the satellites are even harder. Jupiter’s current cloud bands may not be as shown. Image created using Cartes du Ciel (Sky Charts).
| Event | EDT | Universal Time | ||
| Date | Time | Date | Time | |
| Europa Transit Start | March 14 | 09:26 PM | March 15 | 01:26 AM |
| Europa Shadow Start | March 14 | 09:45 PM | March 15 | 01:45 AM |
| Io Shadow Start | March 14 | 10:12 PM | March 15 | 02:12 AM |
| Io Shadow Start | March 14 | 10:21 PM | March 15 | 02:21 AM |
| Europa Transit End | March 15 | 12:12 AM | March 15 | 04:12 AM |
| Io Transit End | March 15 | 12:26 AM | March 15 | 04:26 AM |
| Europa Shadow End | March 15 | 12:33 AM | March 15 | 04:33 AM |
| Io Shadow End | March 15 | 12:36 AM | March 15 | 04:36 AM |
Jovian satellite data from Project Pluto.
Pi Day
Check this out: Pi Day the NASA Way.
Answer to Friday’s Moon phase poser
Of the two representations of the Moon’s terminator last Friday, the Virtual Moon Atlas was the correct representation.
03/11/2016 – Ephemeris – The lunar Sea of Crises
Ephemeris for Friday, March 11th. The Sun will rise at 7:01. It’ll be up for 11 hours and 42 minutes, setting at 6:44. The Moon, 3 days past new, will set at 10:14 this evening.
Tonight the Moon shows one remarkable sea: Mare Crisium or the Sea of Crises. It is a large gray basin. The largest feature visible in binoculars. Because it’s near the Moon’s limb or edge it is foreshortened into an ellipse, with the long axis running north and south. In actuality it is elliptical with the long axis east and west. It looks funny on a geologic map of the whole moon or a Moon globe. Its dimensions are 345 by 375 miles (570 by 620km). It’s really a crater as are all seas whose impact asteroid reached down to the Moon’s magma and caused lava to well up to produce the flat floor. When the sunlight is low as it is now wrinkle ridges will appear showing where successive lava flows have stopped and solidified.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon on its orientation in the southwest at 8 p.m.March 11, 2016. Created using Stellarium.
The Moon at 8 p.m. March 11, 2016 via Virtual Moon Atlas. Note that despite the difference in rotation, that the phase is s bit different. We’ll have to see which one is correct.
Mare Crisium from overhead with Lunar Reconnaissance Orbiter. The vertical lines are due to the north-south scans by the polar orbiting satellite. Credit: NASA/LRO/Virtual Moon Atlas.
