Archive
10/05/2014 – Ephemeris – The Harvest Moon
This is Bob Moler with Ephemeris for Thursday, October 5th. The Sun will rise at 7:45. It’ll be up for 11 hours and 29 minutes, setting at 7:15. The Moon, at full today, will rise at 7:38 this evening.
This is the day of the Harvest Moon. It will rise just before sunset and colored like a huge pumpkin. The huge size is an optical illusion, and the coloring is courtesy of our Earth’s atmosphere selectively bleeding out the blue from the Moon’s light. The reason the Harvest Moon is so special is that during this period the Moon rises for quite a few days just before and in twilight, effectively lengthening the hours of light that farmers can have to harvest their crops. Tomorrow the Moon will rise 32 minutes later than tonight, rather than the average 50 minutes. The effect is a bit diminished this year because the Moon is nearing perigee, its closest to the Earth and is traveling a bit faster than average. The Moon can get down to a 25 minute day-to-day difference.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The position of the Moon for 7 nights centered on moon rise tonight (10/04/2017). The rotation of the Earth carries the Moon to rise parallel to the green celestial equator line. The brown area at the bottom is below the horizon. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
10/04/2017 – Ephemeris – Where are the bright planets tonight?
Ephemeris for Wednesday, October 4th. The Sun will rise at 7:44. It’ll be up for 11 hours and 32 minutes, setting at 7:17. The Moon, 1 day before full, will set at 7:21 tomorrow morning.
Let’s take our weekly look at the bright planets. Jupiter, for all intents and purposes is gone from the evening sky. It will cross into the morning sky later this month. Saturn too is sinking lower in the southwestern sky in the evening. Saturn’s rings are still spectacular in telescopes, but since Saturn is so low in the sky the turbulence of the thick atmosphere makes Saturn fuzzy and seemingly to go in and out of focus. Saturn will set at 10:43 p.m.
In the morning sky, brilliant Venus will rise at 5:11 a.m. in the east with much dimmer Mars below and right of it by half the width of the Moon. Mars is less than 100th the brightness of Venus, and will probably require binoculars to locate. (need a few words more)
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturn and the Moon in the evening at 8 p.m. October 4, 2017. Created using Stellarium.
Saturn and its brightest moons overnight October 4/5, 2017. Created using Cartes du Ciel (Sky Charts).
The Moon as it might be seen in binoculars, 8 p.m. October 4, 2017. Created using Stellarium.
Members of the Grand Traverse Astronomical Society and I are invited to the Chinese Mid-Autumn Festival being held for the Chinese exchange students in the Traverse City school system. Its held on the 15th day of the 8th month of the Chinese lunar calendar, the full moon, which works out to be October 4th this year. They will be having Chinese food and viewing the Moon afterward.
One of the legends celebrated then will be the Jade Rabbit pounding medicine. Jade Rabbit (Yutu) is the name of the Chinese rover that’s on the Moon. And the Jade Rabbit can actually be seen on the Moon:
Jade Rabbit and Mortar on the Moon. Credit: Zeimusu, Creative Commons.
I hope they have Moon Cakes. They sound yummy.
A closeup of Venus and Mars at 6:30 a.m. October 5, 2017. Created using Stellarium.
Planets at sunset and sunrise of a single night starting with sunset on the right on October 4, 2017. The night ends on the left with sunrise on the 5th. The full Moon has fallen in the cracks between the sunset and sunrise charts due to its position south of the ecliptic. Click on the image to enlarge. Created using my LookingUp program.
09/26/2017 – Ephemeris – Saturn appears near the Moon tonight
Ephemeris for Tuesday, September 26th. The Sun will rise at 7:34. It’ll be up for 11 hours and 57 minutes, setting at 7:31. The Moon, 1 day before first quarter, will set at 11:32 this evening.
Tonight the Moon will to be near the planet Saturn. At 9 p.m. the ringed planet will be seen below the crescent Moon. It’s a good way to spot Saturn if you’ve never be able to figure out which of those “stars” in the sky is Saturn. It’s easy to confirm with a small telescope. Even in binoculars Saturn is not quite a star-like point. Saturn’s rings begin to show distinctly with 20 power magnification. The Moon too is great to view at low power, even binoculars. A new sea has appeared since last night. It is the Sea of Serenity above the center of the Moon. The lunar seas are really large nearly circular lava filled craters that appear to have been the result of asteroid impacts about 3.8 or so billion years ago.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturn and the Moon tonight, 9 p.m. September 26, 2017. Created using Stellarium.
The Moon as it might be seen in binoculars, 9 p.m. September 26, 2017. Created using Stellarium.
Compare with last night’s Moon.
The annotated crescent moon tonight, September 25, 2017. Created using Virtual Moon Atlas.
09/25/2017 – Ephemeris – Lets look at the Moon tonight
Ephemeris for Monday, September 25th. The Sun will rise at 7:33 a.m. It’ll be up for 12 hours exactly, setting at 7:33 p.m. The Moon, 2 days before first quarter, will set at 10:52 this evening.
Let’s take a look at the crescent Moon tonight. It will be fairly low in the southwestern sky this evening. Four of the gray lava plains called seas are now visible in binoculars or small telescopes. Nearest the right limb of the Moon is the Sea of Crises, next nearest if the Sea of Fertility. A small sea next to that is the Sea of Nectar. Above that, mostly exposed to sunlight is the Sea of Tranquility. The Sun is just rising at Tranquility Base, where Apollo 11 landed, where the Lunar Module’s descent stage still lies, forlorn and empty. Below that is the beautiful crater Theophilus with its central peak. It is 61 miles (101 km) in diameter, and its crater walls rise over 13,000 feet (4,400 meters) above the crater floor.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The annotated crescent moon tonight, September 25, 2017. Created using Virtual Moon Atlas. Click on the image to enlarge.
The Apollo 11 landing site in one photograph by the Lunar Reconnaissance Orbiter. There are many with varying Sun angles in the Internet. Search for: Apollo 11 LRO images. Credit NASA.
09/12/2017 – Ephemeris – The Moon will hide the bright star Aldebaran after sunrise this morning
Ephemeris for Tuesday, September 12th. The Sun will rise at 7:18. It’ll be up for 12 hours and 40 minutes, setting at 7:58. The Moon, 1 day before last quarter, will rise at 12:13 tomorrow morning.
This morning during daylight at around 8:40*. the bright star Aldebaran will disappear behind the Moon. Binoculars or a small telescope can be used to spot Aldebaran, the bright star in the constellation Taurus the bull’s eye. Taurus and the rest of the winter constellations are visible before sunrise. The sky needs to be absolutely clear to be able to spot the event. The star will be seen to approach the bright side of the Moon. The star will reappear around 9:53 a.m.* on the dark western edge of the Moon. These events are called occultations. They come from the word occult, which means hidden. In actuality the solar eclipse of three weeks ago was a spacial case of an occultation for those in the path of totality.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
* The disappearance and appearance times for Aldebaran are within a couple of minutes for Western Michigan. For other locations in the occultation path Stellarium will give pretty good times for the events by modeling the occultation as I did below. Like a solar eclipse where you are determines the timing of the event.
Addendum
Map of where the occultation is visible. For the area bounded in red, the occultation is visible in the daytime. Credit: Occult4 by IOTA.
Position of the Moon in the sky near the start of the occultation, 8:35 a.m. September 12, 2017. Created using Stellarium.
Aldebaran and the Moon at 8:35 a.m. September 12, 2017. Created using Stellarium.
Aldebaran reappearing from behind the Moon at 9:53 a.m. September 12, 2017. Created using Stellarium.
07/06/2017 – Ephemeris – Saturn will appear near the Moon tonight
Ephemeris for Thursday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:29, and it will rise tomorrow at 6:05. The Moon, 3 days before full, will set at 5:02 tomorrow morning.
The waxing gibbous Moon and the planet Saturn will appear together tonight. They are said to be in conjunction. The brightness of the Moon may make it hard to pick out Saturn which is right under the Moon by about seven Moon diameters. The Moon is very bright in binoculars or a telescope and looking at it destroys the dark adaption in the eye or eyes that look at it, at least for a while. So when viewing both Saturn and the Moon, concentrate of Saturn first. In a telescope Saturn’s rings are glorious. With a good telescope and enough magnification one might see the split in the rings, just inside the outer edge of them called Cassini’s Division, after it’s discoverer. The large moon Titan is off the western extremity of the rings tonight.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon and Saturn at 10:30 p.m., July 6, 2017, as it would be seen from northern Michigan. Created using Stellarium.
Saturn and its rings with Cassini’s Division. Created using Stellarium.
Ring particles at the distance of Cassini’s Division from Saturn orbit the planet twice in the time the satellite Mimas, nicknamed the Death Star, orbits the planet once. Ring particles are thus tugged by Mimas’ gravity away from Saturn in the same place every other orbit, which pulls them out of that particular orbital resonance.
“That’s no moon!” Yes it is. Saturn’s moon Mimas, It’s diameter is 123 miles (198 km). The huge crater is named Herschel, after the moon’s discoverer William Herschel. Credit: NASA / JPL-Caltech / Space Science Institute.
06/09/2017 – Ephemeris – Watch the mini moon rise tonight
Ephemeris for Friday, June 9th. Today the Sun will be up for 15 hours and 29 minutes, setting at 9:26, and it will rise tomorrow at 5:57. The Moon, at full today, will rise at 9:26 this evening.
In recent years we’ve talked about the super moon, when the full Moon appears especially large because it’s at perigee, or closest to the Earth at that time. Well tonight’s full Moon will be a the opposite, a mini Moon. The Moon reached apogee, its farthest from the Earth in it’s orbit at 6:21 last night, and 15 hours later, at 9:10 this morning the Moon was full. However I bet that when the Moon rises tonight that it will appear just as big as it always does, especially if you forget that it’s supposed to be a mini moon. The Moon is in an elliptical orbit of the Earth that this month varies from 252,500 miles (406,400 km) yesterday down to 222,400 miles (357,900 km) on the 23rd. Thanks to the Sun, and especially Jupiter and Venus, those distances change a bit every month. Tonight Saturn will be seen just below the moon.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mini Moon and Super Moon for 2017. Created using Cartes du Ciel (Sky Charts).
06/06/2017 – Ephemeris – Where did the Moon come from?
Ephemeris for Tuesday, June 6th. Today the Sun will be up for 15 hours and 26 minutes, setting at 9:24, and it will rise tomorrow at 5:57. The Moon, 3 days before full, will set at 5:10 tomorrow morning.
The origin of the Moon is a question that has vexed astronomers for years. Did it break off the molten Earth like a cell dividing? Was it captured by passing too close to the Earth? Neither is satisfactory. Chemical elements have different isotopes depending on the number of neutrons in their nucleus. The rocks brought back by the Apollo astronauts show that the isotopes of the elements in the rocks is that same as for the Earth. We know that Mars and the asteroids have different isotope ratios. The hypothesis that seems most likely is that another planet, the size of Mars collided with the 100 million year old Earth in a glancing blow that gave rise to a disk of material that eventually coalesced into the Moon.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The hypothetical collision of a Mars sized body with the young Earth. Credit: Joe Tucciarone via NASA
05/26/2017 – Ephemeris – Can you spot the extremely young Moon tonight?
Ephemeris for Friday, May 26th. Today the Sun will be up for 15 hours and 11 minutes, setting at 9:15, and it will rise tomorrow at 6:03. The Moon, 1 day past new, will set at 10:16 this evening.
It’s spring and a great time to see if you can spot the young moon. The official time when the moon was new was 3:44 p.m. yesterday afternoon (19:44 UT 25 May 2017), which would make the moon a bit less than 31 hours old if spotted before it sets an hour after the Sun. This requires crystal clear skies and a very low northwestern horizon. Binoculars are a definite help. Spotting the earliest moon after new moon is one of the challenges amateur astronomers pit their observing skills with. Another is the Messier Marathon, in which one tries to observe all 110 of Charles Messier’s catalog entries of dim objects on a single night, which is theoretically possible around March 24th.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
A 39 hour old Moon with Jupiter taken by Greg Hogan on September 2, 2016.
I got this from EarthSky.org. Here’s a search I made of the young moon that has some other images: http://earthsky.org/?s=young+moon
05/17/2017 – Ephemeris – Let’s look at the bright planets for this week
Ephemeris for Wednesday, May 17th. Today the Sun will be up for 14 hours and 54 minutes, setting at 9:06, and it will rise tomorrow at 6:11. The Moon, 1 day before last quarter, will rise at 2:20 tomorrow morning.
Let’s take our weekly look at the bright planets. Mars is still in the west-northwest after sunset and fading. It appears under the left edge of the constellation Auriga. It will set at 10:54 p.m. Dominating the evening sky now is Jupiter in the south-southeast. The bright blue-white star Spica is seen below and left of it. In even the smallest telescopes Jupiter’s four largest moons can be seen. They shift positions night from to night and sometimes even as you watch. Jupiter will set at 4:42 a.m. At 5:30 a.m. both Saturn and Venus will be in the morning twilight. Saturn will be low in the south-southwest. It will rise in the east-southeast at 11:14 p.m. Brilliant Venus will be low in the east tomorrow morning after rising at 4:27 a.m.
For us Mercury, at greatest western elongation of 25.8°will be on the horizon at 5:30, but those south of the equator it will be well placed for viewing in the morning.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars and Jupiter with the spring constellations in the fading twilight at 10 p.m., May 17, 2017. Created using Stellarium.
Jupiter and its four Galilean moons as they might be seen in a telescope at 10 p.,. May 17, 2017. Created using Cartes du Ciel (Sky Charts).
Venus, Saturn and the Moon at 5:30 a.m. May 18, 2017. Created using Stellarium. Click on the image to expand.
Saturn and its brightest moons at 5:30 a.m. May 18, 2017. This is displayed at the same scale/magnification as the Jupiter image above. Created using Cartes du Ciel (Sky Charts).
The Moon as it might be seen in binoculars at 5:30 a.m., May 18, 2017. Created using Stellarium.
Venus as seen through a telescope at 5:30 a.m. May 18, 2017. This is displayed at a larger scale/magnification than the Jupiter and Saturn images above. Created using Stellarium.
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on May 17, 2017. The night ends on the left with sunrise on May 18. Click on the image to enlarge. Created using my LookingUp program.
Bob Moler's Ephemeris Blog 