Archive
03/31/2016 – Ephemeris – Tomorrow night’s Astronomy Society meeting
Ephemeris for Thursday, March 31st. The Sun will rise at 7:24. It’ll be up for 12 hours and 45 minutes, setting at 8:09. The Moon, at last quarter today, will rise at 3:39 tomorrow morning.
Tomorrow night the Grand Traverse Astronomical Society will hold it’s monthly meeting with a program featuring a graduate from Northwestern Michigan College and the astronomy program: Becky Shaw who will present a talk on Women in Astronomy. This is a third presentation of female astronomers, who have made important breakthroughs in astronomy. I especially recommend this for girls interested in the STEM fields, that is Science, Technology, Engineering and Math to find out the wonderful contributions these women have made. Astronomy, by the way encompasses all the STEM fields. The meeting starts at 8 p.m. and the observatory is located on Birmley Road, south of Traverse City. At 9 p.m. there will also be star party if it’s clear, viewing the planet Jupiter, the Great Orion Nebula, and other wonders of the heavens.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
03/30/2016 – Ephemeris – The planets tonight – corrected to March 31-April 1
Note: I’ve been under the weather (bad cold) and have been sleeping a lot. The times for the planet phenomena in the second paragraph have been adjusted to the night of March 31st – April 1st.
Ephemeris for Wednesday, March 30th. The Sun will rise at 7:26. It’ll be up for 12 hours and 42 minutes, setting at 8:08. The Moon, 1 day before last quarter, will rise at 2:51 tomorrow morning.
Let’s check out the whereabouts of the bright naked eye planets for the nigh of March 31-April 1, 2016. Jupiter is up at sunset, and will pass due south, astronomers call it a transit, at 12:11 a.m., and will set at 6:41 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 12:49 a.m. in the east-southeast. It’s seen in western Scorpius now. Saturn will rise at 1:30 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 6:55 a.m. again in the east-southeast. Mercury is now in the evening sky but is too close to the Sun to be seen, it will be visible after sunset by mid-month.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter and the evening constellations at 10 p.m. March 31, 2016. Created using Stellarium.
Mars, Saturn and the Moon with the summer constellations at 6 a.m., April 1, 2016. Created using Stellarium.
03/29/2016 – Ephemeris – The Little King Star, Regulus
Ephemeris for Tuesday, March 29th. The Sun will rise at 7:28. It’ll be up for 12 hours and 39 minutes, setting at 8:07. The Moon, 2 days before last quarter, will rise at 2:00 tomorrow morning.
Regulus is the brightest star in the constellation of Leo the lion at the bottom of the backward question mark that is the head and mane of Leo. It’s in the southeast at 9 p.m. above the much brighter Planet Jupiter. Alluding to the lion’s status in the animal kingdom, Regulus is the little king star. It is dead last in order of brightness of the 21 brightest first magnitude stars, 1/13th the brightness of Sirius the brightest star low in the southwest at the same time. To the Babylonians it was the king, the 15th of their constellations that marked the passage of the sun. Regulus is about 79 light years away, and 288 times the brightness of the sun. It is a rapidly spinning ellipsoid 3 times the sun’s diameter, rotating in just under 16 hours.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Regulus and Jupiter in the constellation of Leo at 10 p.m., March 29, 2016. Created using Cartes du Ciel (Sky Charts).
03/28/2016 – Ephemeris – The brightest spring star is now rising in the east
Ephemeris for Monday, March 28th. The Sun will rise at 7:30. It’ll be up for 12 hours and 35 minutes, setting at 8:06. The Moon, 3 days before last quarter, will rise at 1:07 tomorrow morning.
Rising in the eastern sky at 10 p.m. is the 4th brightest night-time star. It’s found off the curve of the handle of the Big Dipper above it in the northeast. It’s the tail end of a kite shaped constellation of Boötes the herdsman. Arcturus is an orange-colored giant star, 37 light years away. Its light was used open the 1933 Chicago Worlds Fair believing its light left the star in 1893 the year of the previous Chicago Worlds Fair. It turns out that Arcturus is 3 light years closer than what they thought. Arcturus is a rapidly moving star. It’s velocity is about 76 miles (122 km) per second. It’s at its nearest to the sun now. Arcturus is thought to be close to the sun’s mass, and much older. It may be a glimpse of what the sun will look like in 5 billion years.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Arcturus off the handle of the Big Dipper rising. Created using Stellarium.
03/25/2016 – Ephemeris – Easter, the reason for our calendar
Ephemeris for Good Friday, Friday, March 25th. The Sun will rise at 7:35. It’ll be up for 12 hours and 26 minutes, setting at 8:02. The Moon, 2 days past full, will rise at 10:17 this evening.
The so-called movable feasts of the church calendar are based on the date Easter falls on. They span from Ash Wednesday to Pentecost. And Easter is determined by astronomical events. In 1582 the fact that the actual vernal equinox had fallen 10 days behind the Julian calendar then in use which was decreed by Julius Caesar in 45 BC. Pope Gregory XIII in the 1580’s resolved to fix the situation and commissioned some astronomers to work on the problem. The solution was to fix the 10 day problem by eliminating the days October 5th through 14th of the October 1582 calendar and modifying the leap year rule to keep February 29th in calendars whose years were evenly divisible by 4, except those century years not also divisible by 400. Thus the year 2000 was a leap year, but 1900 and 2100 was and will not be.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Gregorian Calendar in essence decoupled Easter from Passover by keeping the formula first Sunday after the first full moon after March 21st, as a marker for the vernal equinox, and keeping March 21st on or near the vernal equinox. Passover this year starts sunset on April 22nd, while Orthodox Easter will occur on May 1st. The reason is the relationship between the Jewish lunar calendar and the Julian Calendar I mentioned in yesterday’s post. The difference between the Julian and Gregorian Calendars is now 13 days.
The error in the Gregorian calendar is at most 1 day in 3,300 years, in relation to the seasonal year. But the Gregorian Calendar makes calculating the date of Easter more complicated. It introduces something called Epact to the list of chronological cycles in an almanac. The quantity called Epact is the age of the moon on January 1st, and still has a relationship with the Metonic Cycle and the Golden Number which I discussed yesterday. This year the value is 21.
As I’ve admitted before, the first paragraph of these posts are generated by a computer program. Part of that program is a list of holidays, and those designated as movable feasts use the date of Easter as a starting point. I use the 10 step method from Astronomical Algorithms by Jean Meeus. Easter for the Julian Calendar is a simpler 6 step method.
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.
Bob Moler's Ephemeris Blog 