Archive
03/26/2018 – Ephemeris – The Moon will slide below the Beehive star cluster tonight
Ephemeris for Monday, March 26th. The Sun will rise at 7:34. It’ll be up for 12 hours and 28 minutes, setting at 8:02. The Moon, 2 days past first quarter, will set at 5:34 tomorrow morning.
Tonight the gibbous Moon will be seen among the stars of Cancer the crab. It will just about completely drown Cancer’s dim stars out. That is no exception to one of the famous group of stars in Cancer, the Beehive star cluster. It is going to take binoculars or a small telescope to spot them. The star cluster will be at the 11 o’clock position from the Moon. When looking for the cluster try to keep the Moon out of your field of view. The cluster is about 4 moon-widths away, so aim high and slowly aim those binoculars down. There will be other times in the next few months to catch the Moon near the Beehive, when the Moon will be a not so overwhelming crescent as the cluster moves westward in the evening sky with the rest of the stars.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon and the Beehive Star Cluster tonight at 9 p.m. March 26, 2018. The star cluster will be very difficult to spot. Created using Stellarium, however I had to boost the brightness of the stars and eliminate the atmosphere control to darken the sky enough to see the cluster. Good luck!
Cancer the crab finder chart for a dark night. Note the beehive cluster, also known to amateur astronomers as M44, along with other catalog names. Prior to the invention of the telescope this cluster was known as Praesepe which means “Manger”. Created using Stellarium and GIMP.
03/23/2018 – Ephemeris – After a crazy week sail on the Sea of Serenity
Ephemeris for Friday, March 23rd. The Sun will rise at 7:40. It’ll be up for 12 hours and 18 minutes, setting at 7:59. The Moon, 1 day before first quarter, will set at 2:53 tomorrow morning.
This evening the Moon will be at nearly first quarter and the terminator will be at the edge of the Sea of Serenity or Mare Serenitatis, with the morning Sun shining on its ramparts. Through binoculars or the naked eye the scallop shell shaped sea will be visible at the upper right part of the moon, the man in the moon’s left eye as he is facing us. In telescopes the moon will be inverted and even also reversed, so Serenity could appear in any other quadrant depending on what your telescope does to the image. There are two large craters above or north of Serenity if looking at them with a non-inverting telescope. The nearest to Serenity is Eudoxus, and the farther one is Aristoteles, named after Aristotle.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Tonight’s Moon with the Sea of Serenity and two isolated large craters. 9 p.m., March 23, 2018. Created using Virtual Moon Atlas.
Image of a scallop shell rotated to match the Sea of Serenity. Credit Wikipedia user Kevmin. (Creative Commons)
03/22/2018 – Ephemeris – The bright star Aldebaran will appear below the Moon tonight
Ephemeris for Thursday, March 22nd. The Sun will rise at 7:42. It’ll be up for 12 hours and 15 minutes, setting at 7:57. The Moon, 2 days before first quarter, will set at 1:48 tomorrow morning.
The bright star Aldebaran will appear below the Moon tonight. Over the past two years we’ve seen the Moon cover Aldebaran in an event called an occultation on several occasions. There will be a similar occultation tonight for the far northern part of the Earth. Though the series of Aldebaran occultations won’t end until September this year, we won’t see any of them. The Next season of monthly Aldebaran occultations for the Earth won’t start until 2033. It will last a bit more than 2 years. We’ll see our share of those occultations then. Other bright, first magnitude, stars that can be occulted by the Moon are Pollux in Gemini, Regulus in Leo, Spica in Virgo and Antares in Scorpius.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The star Aldebaran, the bloodshot eye of Taurus the bull at 9 p.m. tonight, March 22, 2018 to be seen below the crescent Moon. The rest of the face of Taurus, the V-shaped stars of the star cluster called the Hyades will be visible in binoculars. Created using Stellarium. The Moon will be brighter than Aldebaran, not the opposite as seen here.
03/21/2018 – Ephemeris – The bright planets this week
Ephemeris for Wednesday, March 21st. The Sun will rise at 7:44. It’ll be up for 12 hours and 12 minutes, setting at 7:56. The Moon, 3 days before first quarter, will set at 12:39 tomorrow morning.
Let’s take our weekly look at the bright planets. All 5 of the naked eye planets are visible now. Two of them are in the evening sky, but very close to the Sun. Venus will be visible low in the Western twilight from about 8:10 p.m. until before it sets at 9:26. Mercury is much dimmer but at the same height and to the right of Venus, tonight by about 8 Moon widths. Mercury is dimming rapidly. In the morning Jupiter will rise at 12:20. Mars will rise at 3:33. Saturn will end the procession, rising at 3:53 a.m. At 7 tomorrow morning these three planets will be strung across the southern sky. Bright Jupiter will be in the southwest, dimmer Mars will be in the south. Saturn will be in the south-southeast.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The morning planets of Jupiter, Mars and Saturn seen at 7 a.m. EDT this morning March 21, 2018. Click on image to enlarge. Created using Stellarium.
Jupiter and Saturn with their brighter satellites this morning at 7 a.m. March 21, 2018. They are displayed at the same scale. Saturn in about twice as far as Jupiter. Its disk is a bit smaller than Jupiter’s so it appears about half as large. The extent of the rings appear to be about the same as Jupiter’s diameter. Created using Cartes du Ciel (Sky Charts).
Jovian satellite events this morning
Satellite Event Date Universal Local Time Ganymede: Eclipse start: 21 Mar 2018 7:30 UT 3:30 am EDT Io : Shadow start: 21 Mar 2018 8:08 UT 4:08 am EDT Io : Transit start: 21 Mar 2018 9:09 UT 5:09 am EDT Ganymede: Eclipse end : 21 Mar 2018 9:15 UT 5:15 am EDT Io : Shadow end : 21 Mar 2018 10:18 UT 6:18 am EDT Io : Transit end : 21 Mar 2018 11:17 UT 7:17 am EDT Ganymede: Occultation start: 21 Mar 2018 11:50 UT Not visible Ganymede: Occultation end : 21 Mar 2018 12:54 UT Not visible
An eclipse is when the moon passes through Jupiter’s shadow.
An occultation is when the moon is hidden behind the planet.
Shadow denotes the projection of a satellite’s shadow on the face of Jupiter.
Transit is the passage of a satellite across the face of Jupiter. It becomes hard to find against the.
Timings are from https://www.projectpluto.com.
Venus and Mercury, low in the west at 8:30 p.m., March 21, 2018. Created using Stellarium.
The waxing crescent Moon as it might be seen in binoculars at 9 p.m. tonight. March 21, 2018. Created using Stellarium.
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on March 21, 2018. The night ends on the left with sunrise on the 22nd. Click on the image to enlarge. Created using my LookingUp program.
03/20/2018 – Ephemeris – Spring begins later today!
Ephemeris for Tuesday, March 20th. The Sun will rise at 7:45. It’ll be up for 12 hours and 9 minutes, setting at 7:55. The Moon, 3 days past new, will set at 11:30 this evening.
At 12:15 p.m. the season of spring will begin. It may or may not feel it in our neck of the woods, but astronomically at that time the Sun will appear to cross a point in the sky called the vernal equinox. Equinox means equal night, when the Sun is up for 12 hours, and set for 12 hours. It does, if you don’t look too close, and in the old days clock weren’t that accurate anyway. The vernal equinox is the point in the sky where the Sun crosses the celestial equator, which is above the Earth’s equator heading north. The North Pole will begin 6 months of daylight, while the rest of the northern hemisphere will bask in more than 12 hours of sunlight a day. The reverse is true in the southern hemisphere where autumn will start.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Sun at the vernal equinox point in the sky at 12:15 p.m. EDT (16:15 UT) March 20, 2018. That point is the starting point in measurements on the celestial sphere. 0 hours right ascension, 0 degrees declination. The yellow line is the ecliptic, the plane of the Earth’s orbit and the apparent path of the Sun, whivh moves about one degree per day from lower right to upper left. Created using Cartes du Ciel (Sky Charts).
The Earth from 2 days before the vernal equinox, with the north pole not quite in sunlight. I’ve added a magnifying spot showing Michigan. The white stuff fringing the upper part of the Michigan mitten is snow. It was a rare clear day Saturday when this image was taken. Credit NOAA/NASA/DSCOVR satellite/EPIC camera.
The DSCOVR satellite was 914,903 miles (1,472,394 km) sunward of the Earth at the time of the image. The satellite is in a halo orbit of the Lagrangian L1 point between the Earth and the Sun.
03/19/2018 – Ephemeris – The dim zodiacal constellation of Cancer the crab
Ephemeris for Monday, March 19th. The Sun will rise at 7:47. It’ll be up for 12 hours and 6 minutes, setting at 7:54. The Moon, 2 days past new, will set at 10:21 this evening.
At 10 this evening, the faint constellation, and member of the Zodiac, Cancer the crab is located in the south half way between the bright stars Castor and Pollux of the constellation Gemini, high in the south and the bright star Regulus in Leo the lion in the southeast. Cancer is very dim, looking like an upside-down Y or even a K if all its stars can be made out. In the center of Cancer is a fuzzy spot to the unaided eye. In binoculars or a low power telescope this fuzzy spot becomes a cluster of stars. It is the Beehive cluster. At 577 light years away, according to the latest measurements, it is one of the closest star clusters. A week from tonight the Moon will pass below this cluster, by about 4 of its diameters.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Cancer the crab finder chart. Note the beehive cluster, also known to amateur astronomers as M44, along with other catalog names. Prior to the invention of the telescope this cluster was known as Praesepe which means “Manger”. Created using Stellarium and GIMP.
The Beehive star cluster, M44. Its ancient name was the Praesepe or manger when glimpsed by the naked eye. Created using Cartes du Ciel (Skycharts)
03/16/2018 – Ephemeris – The Moon and evening planets this weekend
Ephemeris for Friday, March 16th. The Sun will rise at 7:53. It’ll be up for 11 hours and 56 minutes, setting at 7:50. The Moon, 1 day before new, will rise at 8:13 tomorrow morning.
The Moon will very close to new this weekend, so the dark skies can be enjoyed after 9:30 in the evening for hard-core dark sky observers. However after 9 p.m. it’s dark enough for most of us. The Moon next week will rapidly push that back as its phase waxes over the next week toward first quarter. About the first appearance of the Moon will be Sunday night when it will be almost in line with Venus and Mercury. Top right will be Mercury, then Venus, then below and left of brilliant Venus will be the thin sliver of the crescent Moon, whose night side will be illuminated by the Earth. It will take binoculars to really appreciate this Earth shine on the Moon. The full Moon this lunation will fall on the 31st with Easter following the next day for western churches.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mercury, Venus, and the Moon at 8:15 p.m. Sunday, March 18, 2018. Created using Stellarium, which was incapable of showing the very thin crescent of the Moon centered at the 5 o’clock limb of the Moon..
03/15/2018 – Ephemeris – Mercury at greatest separation (elongation) from the Sun today
Ephemeris for the Ides of March, Thursday, March 15th. The Sun will rise at 7:55. It’ll be up for 11 hours and 53 minutes, setting at 7:48. The Moon, 2 days before new, will rise at 7:45 tomorrow morning.
Today the planet Mercury will be at its greatest separation east from the Sun. It is called its greatest eastern elongation from the Sun. It is at an angle of 18.4 degrees from the Sun. It will be seen in the west about 8:15 for about an hour before it sets. It will be above right of the much brighter Venus. Mercury is probably at its best place to be observed than any time this year, with eastern elongation happening near the vernal equinox and is placed at a high angle above the Sun. The best morning appearance of Mercury will be its greatest western elongation on August 26th, almost a month short of the autumnal equinox, where it won’t be placed at as great an angle above the rising Sun.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus and Mercury photographed last night at 8:20 EDT March 14, 2018. Did some tweaks to bring out Mercury in GIMP. Canon EOS Rebel T5, 75 mm, though reduced by 67%; f/4, 1/400 sec., ISO 1600. Click on image to enlarge. Click on image to enlarge. Credit Bob Moler.
Stellarium’s showing of Venus and Mercury at 8:15 p.m. March 15. 2018.
Note in the above image, the steepness of the ecliptic (plane of the Earth’s orbit) is to the horizon in the spring. Its angle to the celestial equator is 23.5°. The angle the celestial equator makes with the horizon is your co-latitude (90° – your latitude). At my location my latitude is 44.7°, so the celestial equator meets the horizon at 45.3°. On the March equinox the ecliptic, near where the planets hang out, reaches its most vertical at nearly 70°. This makes planets, including Mercury appear higher in the sky near sunset, and as they set, moving parallel to the equator, will stay up their longest.
Celestial equator and ecliptic at the September equinox showing how low it appears. Created using Stellarium.
On the September equinox the ecliptic, near where the planets hang out, reaches its most horizontal at near 22°. This makes planets, including Mercury appear lower in the sky near sunset, and as they set, moving parallel to the equator, will set shortly after the Sun. This September Venus happens to be approaching its inferior conjunction and is very close to the Earth. This exaggerates its orbital inclination. in this case shows the planet a good deal south of the ecliptic.
At the spring equinox close morning planets to the Sun will be hard to spot, being low to the horizon.
Celestial equator and ecliptic at the September equinox mornings showing how high it appears. Created using Stellarium.
Update
The angles of the elongation of Mercury at the equinoxes. Click on image to enlarge. Created using my LookingUp program.
Due to the eccentricity of Mercury’s orbit and its orientation with respect to the Earth’s positions at the equinoxes, observers on the southern hemisphere of the Earth get a better view of Mercury than us northerners.
(I created a similar diagram for posting yesterday, but found right before the scheduled posting time that it was incorrect in its orientation, so I redid it this morning.)
03/14/2018 – Ephemeris – A Pi Day look at the bright planets
Ephemeris for Pi Day, Wednesday, March 14th. The Sun will rise at 7:57. It’ll be up for 11 hours and 50 minutes, setting at 7:47. The Moon, 3 days before new, will rise at 7:15 tomorrow morning.
Pi day: the first three digits of the mathematical constant pi is 3-14. Let’s take our weekly look at the bright planets. All 5 of the naked eye planets are visible now. Three of them are visible this morning. Before it gets light Jupiter will be in the west-southwest, with Mars in the south and Saturn a bit left of the red planet. Jupiter will rise at 12:44 tomorrow morning. Mars will rise at 3:42. And Saturn will rise at 4:19 a.m. In the evening sky Venus will be visible low in the western twilight from about 8:15 p.m. until before it sets at 9:06. Mercury is much dimmer but above and a bit right of Venus, tonight about 8 Moon widths at 1 o’clock from Venus. It will set at 9:26. Mercury will appear higher than Venus in the sky for 6 more nights.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The morning planets of Jupiter, Mars and Saturn plus the Moon. Seen at 7 a.m. EDT this morning March 14, 2018. Click on image to enlarge. Created using Stellarium.
Jupiter and Saturn with their brighter satellites tomorrow morning at 6 a.m. March 8, 2018. They are displayed at the same scale. Saturn in about twice as far as Jupiter. Its disk is a bit smaller than Jupiter’s so it appears about half as large. The extent of the rings appear to be about the same as Jupiter’s diameter. Created using Cartes du Ciel (Sky Charts).
Venus and Mercury, low in the west at 8:15 p.m., March 14, 2018. Created using Stellarium.
Planets at sunset and sunrise of a single night starting with sunset on the right on March 14, 2018. The night ends on the left with sunrise on the 15th. Click on the image to enlarge. Created using my LookingUp program.
02/13/2018 – Ephemeris – The Big Dipper as a pointer to other stars and constellations
Ephemeris for Tuesday, March 13th. The Sun will rise at 7:58. It’ll be up for 11 hours and 47 minutes, setting at 7:46. The Moon, 4 days before new, will rise at 6:42 tomorrow morning.
With the Big Dipper up in the northeastern sky it is a sign that spring is coming. At 9 p.m. The Big Dipper can be used to find other stars and constellations. The Big Dipper’s most famous function is in locating Polaris the North Star. It’s a good way of finding directions at night. The altitude of Polaris, that is angle above the horizon, will give one’s approximate latitude north of the equator. Another constellation that can be found is Leo the lion. It is rising in the east in the evening, but it can also be found from the Big Dipper by imagining that a hole were drilled in the bottom of the bowl to let the water leak out. It would fall on Leo’s back. The Big Dipper can be used to find two more stars, but they have not yet risen.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Big Dipper points to Polaris, the, North Star, and to Leo the lion at 9 p.m., March 13th. In another hour the 4th brightest night-time star Arcturus will appear above the eastern horizon pointed to by the arc of the handle of the Big Dipper. We’ll revisit the Big Dipper next month when Arcturus and Spica will also be found by the use of the Big Dipper. Created using Stellarium and Libre Office.
