Archive
05/17/2016 – Ephemeris – Three heliocentrists memorialized on the Moon tonight
Ephemeris for Tuesday, May 17th. Today the Sun will be up for 14 hours and 55 minutes, setting at 9:07. The Moon, half way from first quarter to full, will set at 4:50 tomorrow morning. Tomorrow the Sun will rise at 6:10.
Tonight the gibbous Moon boasts the uncovering of three craters from lunar night whose namesakes were pioneers in putting forth the heliocentric theory. That is that the Earth and the other planets revolved about the Sun. Out the longest, and making the biggest splash is the crater Copernicus, named for the Polish cleric whose book On the Revolution of the Heavenly Spheres gave a new meaning to the word revolution, that is upheaval. The crater Kepler is about two-thirds the way from Copernicus and the terminator, named after the astronomer who discovered that the plants orbit the Sun in elliptical paths. Finally just catching sunlight is Aristarchus who in the 4th century BC first proposed a heliocentric solar system.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Three heliocentrists on the Moon at 10 p.m., May 17, 2016. Created using Virtual Moon Atlas.
05/16/2016 – Ephemeris – The Sun rises on the Bay of Rainbows
Ephemeris for Monday, May 16th. Today the Sun will be up for 14 hours and 53 minutes, setting at 9:06. The Moon, 3 days past first quarter, will set at 4:23 tomorrow morning. Tomorrow the Sun will rise at 6:11.
One of my favorite lunar formations is creeping into sunlight on the Moon this evening. Look to the upper left edge of the moon tonight. The large sea or dark area of the Moon, the Man in the Moon’s right eye as he’s looking at us is Mare Imbrium, the Sea of Showers. At the top left edge of that sea is a large notch. And keeping with of seas these of the first telescopic astronomers its name is Sinus Iridium, or Bay of Rainbows, a colorful name for something as colorless as the rest of the Moon. The terminator which is the sunrise line will be cutting across that bay, illuminating the semicircular mountain ring that surrounds it before all of the floor is illuminated. It can be seen in binoculars or a small telescope.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Image showing the Moon tonight at 10 p.m., May 16, 2016 (2 hr, May 17, 2016 UT) with Sinus Iridium (Bay of Rainbows) just coming into sunlight. Created using the Virtual Moon Atlas.
05/13/2016 – Ephemeris – GTAS Astronomy Day tomorrow
Ephemeris for Friday, May 13th. Today the Sun will be up for 14 hours and 46 minutes, setting at 9:02. The Moon, at first quarter today, will set at 2:59 tomorrow morning. Tomorrow the Sun will rise at 6:15.
The Grand Traverse Astronomical Society will host a public viewing night for Astronomy Day tomorrow night, that’s Saturday the 14th, starting at 9 p.m. It will be at Northwestern Michigan College’s Joseph Rogers Observatory. If its clear the slightly gibbous moon will be featured along with Jupiter, Mars and the ringed planet Saturn and other wonders of the spring sky. The observatory is located south of Traverse City, on Birmley Road between Garfield and Keystone roads. For the society these, twice monthly star parties at the observatory and sidewalk astronomy outings by members, to the Sleeping Bear Dunes National Lakeshore and other locations are what they do.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Other thoughts
I was checking out the Solar and Heliospheric Observatory (SOHO) LASCO C3 animation and Venus is making an entrance from the right as it heads for superior conjunction on June 6. June 6? Hmm. Wasn’t that last transit or Venus on June 5th 2012. We and Venus should be near the line of nodes again, where the planes of our respective orbits cross. I cranked up Stellarium, and sure enough the Sun will occult Venus that day… Not that we could see it.
05/12/2016 – Ephemeris – The Moon tonight
Ephemeris for Thursday, May 12th. Today the Sun will be up for 14 hours and 44 minutes, setting at 9:01. The Moon, 1 day before first quarter, will set at 2:26 tomorrow morning. Tomorrow the Sun will rise at 6:16.
The moon tonight is a fat crescent. In binoculars the small Sea of Crises is prominently located as a gray patch at the edge of the moon. The Sea of Fertility is below it, while the sea of Tranquility is between them and near the terminator, the sunrise line on the moon. In telescopes there are three craters south of Tranquility, most prominent of which is Theophilus. With its prominent central peak. Farther to the north of Crises and near the partially exposed Sea of Serenity is the crater Posidonius, larger than Theophilus, but has a double crater wall on one side. Larger telescopes can see cracks in its floor . It has no central peak, and shows its age of maybe three and a half billion years.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon at 10 p.m. May 12, 2016. Created using Virtual Moon Atlas.
05/11/2016 – Ephemeris – Three of the bright planets are seen before midnight
Ephemeris for Wednesday, May 11th. Today the Sun will be up for 14 hours and 41 minutes, setting at 9:00. The Moon, 2 days before first quarter, will set at 1:48 tomorrow morning. Tomorrow the Sun will rise at 6:17.
Let’s see what the bright naked eye planets are up to. Mercury is now officially in the morning sky but too close to the Sun to be seen. Jupiter is in the south in the early evening, and will pass due south at 9:22 p.m., and will set at 3:55a.m. It’s below the stars of Leo this year. Binoculars can make out some of Jupiter’s moons, but a telescope is required to see all four bright moons and Jupiter’s cloud features. Mars will rise at 10:33 p.m. in the east-southeast. It’s still above its look-a-like star Antares, whose name means Rival of Mars. Mars is getting closer to the Earth now, only 50 million miles away It will be closest on the 30th. Saturn will rise at 10:41 p.m. in the east-southeast. It’s just left of Mars.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The evening sky tonight at 11:30 p.m. Created using Stellarium.
05/10/2016 – Ephemeris – The lunar Sea of Crises
Ephemeris for Tuesday, May 10th. The Sun rises at 6:19. It’ll be up for 14 hours and 39 minutes, setting at 8:59. The Moon, 3 days before first quarter, will set at 1:04 tomorrow morning.
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’s approximate orientation and phase at May 10, 2016. Created using Stellarium.
Some views of the festivities at the Sleeping Bear Dunes National Lakeshore Dune Climb for the transit of Mercury earlier today
Mercury and some sunspots at 8:30 a.m. through my telescope. Thought I’d take a shot before we had visitors. C8 Cassigrainian focus, ISO 100, 1/100 second.
Checking the transit via the “Dobinator” through the Grand Traverse Astronomical Society’s (GTAS) 25 inch Dobsonian stopped down with an 8″ solar filter.
Viewing the transit through my Celestron C8.
Kids viewing the transit through the society’s Lunt hydrogen alpha solar telescope.
Youngster viewing the transit through Emmett Holmes’ 13″ homemade Dobsonian telescope and Poncet tracking mount.
Credit: Bob Moler
05/09/2016 – Ephemeris – The transit of Mercury is today!
Ephemeris for Monday, May 9th. The Sun rises at 6:21. It’ll be up for 14 hours and 36 minutes, setting at 8:58. The Moon, 3 days past new, will set at 12:12 tomorrow morning.
In less than an hour from now the planet Mercury will begin to cross the face of the Sun. It starts at 7:12 a.m. The transit will end at 2:42 this afternoon. Mercury is a tiny planet making a tiny dot against the face of the Sun, and smaller than any sunspot. If it’s clear or when its clear come out and view part of the transit. The Northwestern Michigan College’s Rogers Observatory will be open for that period. Also telescopes with be stationed at the Dune Climb at the Sleeping Bear Dunes National Lakeshore by yours truly to view the transit. The event is not visible to the naked eye and dangerous to even attempt. If you miss this transit, there will be another in 2019, 3 ½ years from now. After that, a Mercury transit visible from here will have to wait until 2049.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The track of Mercury across the face of the Sun. Mercury will travel from upper left to lower right. Mercury will not be visible until it impinges upon the disk of the Sun. Credit IOTA’s program Occult4.
Transit visibility map with added captions to make it more readable. Credit United States Naval Observatory, The Astronomical Almanac Online.
For more information see my prior day’s posts.
Ephemeris Extra – Transit of Mercury
Transit of Mercury – May 9, 2016*
Monday, May 9th the planet Mercury will cross in front the Sun in an event called a transit. Transits of Mercury are not as rare as those of Venus. No one alive who saw that last transit of Venus, will see the next in 2117. The last transit of Mercury was in 2006, and the next will be in 2019, though it’s a long jump to the transit after that in 2032.
Occult4’s geocentric ingress time is 7:12 a.m. (11:12 UT) at position angle 83.1° Farthest penetration onto the Sun’s face is 10:57 a.m. (14:57 UT) Egress time is 2:42 p.m. (18:42 UT) at position angle 224.4°. Position angle is measured from the North point on the Sun counterclockwise.
The track of Mercury across the face of the Sun. Mercury will travel from upper left to lower right. Mercury will not be visible until it impinges upon the disk of the Sun. Credit IOTA’s program Occult4.
Looking at the Sun normally from northern Michigan, Mercury’s ingress point is close to the 8 o’clock point on its edge, since the Sun will rise tilted to the left nearly 45°. Mercury is tiny, 6.8 seconds of arc in diameter, and will be very hard to spot, smaller than most sunspots. Venus was nearly 58 seconds of arc in diameter when it transited the Sun in 2012.
Since Mercury is invisible before the transit starts. Checking out the Sun in the telescope and moving it in right ascension and declination or altitude and azimuth and altitude so the ingress point can be determined. Newtonian telescopes give an upside down image, actually rotated 180°. Refractors and Schmidt or Maksutov telescopes generally give a mirror reversed image due to the diagonal mirror that the eyepiece is placed into. The image is right side up or upside down depending on the rotation of the diagonal.
The use of a Hydrogen Alpha solar telescope allows an early peek at the transit. These telescopes look at the Sun’s chromosphere, a layer of gas 6,000 miles thick directly above the photosphere. Since the chromosphere is twice as thick as the diameter of Mercury. This should give you a few minutes heads up before white light telescopes can spot the start of the transit. I noticed the effect with the transit of Venus in 2012.
Parts of the Earth facing the Sun at the start of the transit (Left) and the end of the transit (Right). At the start of the transit Michigan is near the limb of the Earth at the upper left. The transit starts about 51 minutes after sunrise in norther Michigan. From Occult 4.
The only way to view the transit in white light is with a telescope with a front mounted solar filter. Using an eyepiece to project an unfiltered telescope image with an eyepiece may work, but Mercury is very small and projecting the Sun’s image in the ambient light doesn’t give a contrasty image.
To help everyone out the Grand Traverse Astronomical Society will have telescopes in two locations: The NMC Rogers Observatory and the Dune Climb at the Sleeping Bear Dunes National Lakeshore. Since the transit lasts 6 ½ hours the usual cancellation rules won’t be in effect. If it’s cloudy at the start, it could clear up later on. I’ll be stationed at the Dunes and will be there for the duration, so if we have an all day rain I’ll still be out there, hoping it’ll clear up. Check bobmoler.wordpress.com for the latest on viewing conditions there.
* Based on my article in the May 2016 edition of the Stellar Sentinel, the monthly publication of the Grand Traverse Astronomical Society.
05/06/2016 – Ephemeris – Learn about Monday’s transit of Mercury tonight
Ephemeris for Friday, May 6th. The Sun rises at 6:25. It’ll be up for 14 hours and 29 minutes, setting at 8:54. The Moon is new today, and won’t be visible.
Learn more about next Monday’s transit of Mercury across the Sun at tonight’s meeting of the Grand Traverse Astronomical Society at 8 p.m. at the Northwestern Michigan College’s Rogers Observatory, on Birmley Road, South of Traverse City. Afterward at 9 p.m., there will be another program and weather permitting there will be viewing of Jupiter, and later Mars. On Monday the Society will host transit viewing at two locations. The transit runs 6 ½ hours from 7:12 a.m. to 2:42 p.m. The Rogers Observatory will be open for that period. Also telescopes with be stationed at the Dune Climb at the Sleeping Bear Dunes National Lakeshore by yours truly to view the transit. The event is not visible to the naked eye and dangerous to even attempt it.
The program will also preview the coming opposition of Mars and closest approach since 2003 on the 30th.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
I posted these yesterday, but here they are again:
Transit visibility map with added captions to make it more readable. Credit United States Naval Observatory, The Astronomical Almanac Online.
The track of Mercury across the face of the Sun. Mercury will travel from upper left to lower right. Mercury will not be visible until it impinges upon the disk of the Sun. Credit IOTA’s program Occult4.
From IOTA’s Occult4 program
Transit of Mercury on 2016 May 9 (TT)
{'+' => next day; '-' => previous day }
Overhead at
Geocentric Event UTC P.A. Long Lat
h m s o o o
[1] Exterior Ingress 11 12 16 83.1 11 17
[2] Minimum Separation 14 57 38 -45 18
[3] Exterior Egress 18 42 23 224.4 -102 18
Minimum sepn 318.5"; Radii - Sun 950.4", Mercury 6.0"
delta T = 68.2 secs, Ephemeris = DE0
Note: These timings are geocentric. Occult4 has timings for various cities of the world. Occult4.0.2 can be downloaded here. They can vary by several minutes for different cities due to parallax.
I will post more information on the transit in an Ephemeris Extra tomorrow.
Bob Moler's Ephemeris Blog 