Archive
09/23/2013 – Ephemeris – Motions of the Moon
Ephemeris for Monday, September 23rd. The sun will rise at 7:31. It’ll be up for 12 hours and 6 minutes, setting at 7:37. The moon, 3 days before last quarter, will rise at 9:57 this evening.
The moon has two motions, as I see it in the sky. As the earth rotates, it appears to carry the moon and all the other celestial objects westward each day and night. It so happens that the earth rotates one degree in 4 minutes. The moon and sun happen to be about a half degree in size, so the will appear to move their diameters in 2 minutes. Since around here they rise and set at a 45 degree angle, more or less, the rising and setting of the moon and sun take about 3 minutes. The moon also orbits the earth. It’s orbital velocity is about 2,000 miles an hour. And since the moon is 2,160 miles in diameter, its orbital velocity moves it about its diameter in an hour against the stars. That’s why central solar eclipses last about 2 hours, One hour in and one hour out.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The 1 hour motion of the moon as it orbits the earth. This is for September 23, 2013. Created using Cartes duCiel (Sky Charts).
09/20/2013 – Ephemeris – The September equinox and astronomy at Fishtown
Ephemeris for Friday, September 20th. The sun will rise at 7:27. It’ll be up for 12 hours and 15 minutes, setting at 7:43. The moon, 1 day past full, will rise at 8:11 this evening.
At 4:44 in the afternoon Sunday autumn will begin. More important and sad for me is that summer will also end. Since March 20th the sun has been north of the celestial equator, shining directly over some part of the northern hemisphere tropics, but Sunday it moves south of the equator, causing sunset at the north pole and sunrise at the south pole. That point in time is called the autumnal or September equinox. In a few days daylight hours here will drop below 12 hours and keep on dropping until we near Christmas. On a brighter note: During the day Saturday, that’s tomorrow, the Grand Traverse Astronomical Society will have their telescopes down at Fishtown for the Leland Heritage Celebration, that’s 10 am to 5 p.m. in Leland Michigan.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Earth looking from the direction of the sun at the moment of the Autumnal Equinox, 4:44 p.m.EDT September 22, 2013. Created using Celestia.
GTAS at Fishtown in 2011.
09/19/2013 – Ephemeris – Talk like a Pirate Day and the Harvest Moon
Aye mateys this is Cap’n. Bob with Ephemeris for Talk like a Pirate Day Thursday, September 19th. Arrr. That’s the extent of it for me. The sun will rise at 7:26. It’ll be up for 12 hours and 18 minutes, setting at 7:45. The moon, at full today, will rise at 7:39 this evening.
This is the Harvest Moon, the closest full moon to the autumnal equinox, which is four days away. It is the most famous and useful of the full moons of the year. In the days before electric lights, the bright moon, rising before and just after sunset extended twilight and allowed farmers extra light to gather in the crops. It is this part of the moon’s cycle that it rises much less than the average 50 minutes later each night. It will rise only 26 minutes later tomorrow night. The moon is in a part of its orbit in which it is most rapidly moving northward and is also staying out longer each night. We will be seeing the bright moon in the early evening for the next few days.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon on 5 nights at 8:30 p.m. for September 17 to the 21st, 2013 showing the Moon’s northerly motion. Created using Cartes duCiel.
09/18/2013 – Ephemeris – Saturn and Venus appear closest tonight and the rest of the bright planets
Ephemeris for Wednesday, September 18th. The sun will rise at 7:25. It’ll be up for 12 hours and 21 minutes, setting at 7:46. The moon, 1 day before full, will set at 7:38 tomorrow morning.
Time again to check out the bright planets. Saturn and Venus will be closest together tonight, low in the southwest after sunset. Dimmer Saturn will be on top. Binoculars may be needed to spot it. Venus will set at 9:13 p.m., while Saturn will set at 9:32. We will soon lose Saturn in the sun’s glare for a few months. The rest of the planetary action will be in the morning sky. The giant planet Jupiter will rise at 1:22 a.m. in the east northeast. It’s cruising against the stars of Gemini this viewing season. By 6 a.m it will be high in the east southeast, the brightest object in that direction. Mars will rise at 3:39 a.m. also in then east northeast. It is a bright reddish second magnitude star passing through Cancer now.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus and Saturn at 8:30 p.m. on September 18, 2013. Created using Stellarium.
Jupiter and Mars against the constellations of Winter at 6 a.m. on September 18, 2013
09/17/2013 – Ephemeris – How did the moon form?
Ephemeris for Tuesday, September 17th. The sun will rise at 7:23. It’ll be up for 12 hours and 24 minutes, setting at 7:48. The moon, 2 days before full, will set at 6:27 tomorrow morning.
The question of how the moon formed has long been a mystery. It was considered impossible that the earth could capture such a large body all by itself. An answer came from the age of the Apollo Moon missions. Though the moon has a 64th the earth’s volume, it has only an eighty-first of the earth’s mass, hence it was made of lighter material overall than the earth. The Moon is made of the same material as the crust of the earth. Even the isotopes of the elements matched, extremely odd if the Moon was the result of a capture or collision with the already formed earth. A new theory posited last year has the earth and moon forming from a collision of two large-sized bodies, whose material was mixed to then form the Earth and Moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Collision of Mars sized body with the early Earth. A newer theory posited a more equal sized bodies. Credit: NASA
09/16/2013 – Ephemeris – The brightest spot on the moon
Ephemeris for Monday, September 16th. The sun will rise at 7:22. It’ll be up for 12 hours and 27 minutes, setting at 7:50. The moon, 3 days before full, will set at 5:15 tomorrow morning.
The moon is very bright tonight and almost painful to view through a telescope. Remember that’s the full strength of the sun shining on it. Be thankful that it reflects only about 11 percent of the sunlight that hits it. Just thing how much brighter it would be if it was covered by Lake Michigan beach sand. There is a bright spot on the moon now visible. It just became visible today. It’s a crater at the upper left of the moon that’s called Aristarchus after the ancient Greek Philosopher who came up with the sun centered solar system in the 3rd century BC. Unfortunately all his writings have been lost. We only have the comments from others of what he wrote. The crater is the brightest spot on the moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The location of Aristarchus on the moon at 9 p.m. September 16, 2013. Created using Virtual Moon Atlas.
The crater Aristarchus. Credit: Lunar and Planetary Institute.
09/13/2013 – Ephemeris – Star party this weekend
Ephemeris for Friday, September 13th. The sun will rise at 7:19. It’ll be up for 12 hours and 37 minutes, setting at 7:56. The moon, 1 day past first quarter, will set at 1:41 tomorrow morning.
Saturday evening from 9 to 11 p.m. The Grand Traverse Astronomical Society will be out at Northwestern Michigan College’s Rogers Observatory on Birmley Road, south of Traverse City for a Star Party. There will be a glimpse of Venus and Saturn at the beginning of the evening. The moon will be a great sight in telescopes. The society’s CCD camera can show the detail on the moon so actual formations can be pointed out. The CCD camera was purchased by the society to allow the handicapped and folks afraid of ladders to view some of the heavenly objects from terra firma. Other telescopes will allow a direct view of the moon. Some of the brighter objects beyond the solar system, we call them deep sky objects, can also be viewed if it’s clear.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon at 9 p.m. September 14, 2013. We’ll take you on a tour Saturday night, Created using Virtual Lunar Atlas.
09/12/2013 – Ephemeris – A look at the first quarter moon
Ephemeris for Thursday, 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, at first quarter today, will set at 12:36 tomorrow morning.
By this evening the moon will be just past first quarter and the terminator will bulge a bit to the east. 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. 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. Toward the terminator from Serenity are two mountain ranges The south part is the Apennines, and the northern part is the Alps. The Alps is cut by a gash called the Alpine Valley. There’s also a triangle of distinctive craters also visible near the terminator.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
First quarter Moon with some of the features on its northern hemisphere. Created using Virtual Moon Atlas.
09/11/2013 – Ephemeris – Where are all the bright planets this week?
Ephemeris for Wednesday, September 11th. The sun will rise at 7:16. It’ll be up for 12 hours and 43 minutes, setting at 8:00. The moon, 1 day before first quarter, will set at 11:39 this evening.
Lets see what bright planets are out this week. Venus is now brilliant low in the west southwestern sky in evening twilight. It will set at 9:24 p.m. Saturn is about 8 degrees above and to the left of Venus. That’s a bit less that the width of a fist held at arm’s length. It has a date with Venus on the 18th. Saturn will set at 9:58 p.m. After midnight Jupiter will rise at 1:45 a.m. in the east northeast. Jupiter is seen among the stars of Gemini this year. The red planet Mars will rise at 3:43 a.m. Currently it is moving rapidly eastward through Cancer. At about 6 a.m. Jupiter will be the brightest star-like object in the east, with Mars visible below and left by two and a half widths of your fist held at arm’s length.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturn and Venus at 9 p.m. September 11, 2013. Created using Stellarium.
Jupiter and Mars with a preview of the winter constellations at 6 a.m. September 12, 2013. Created using Stellarium.
09/10/2013 – Ephemeris – The Moon reveals the Apollo 11 landing site
Ephemeris for Tuesday, September 10th. The sun will rise at 7:15. It’ll be up for 12 hours and 46 minutes, setting at 8:02. The moon, 2 days before first quarter, will set at 10:49 this evening.
Tonight the moon will reveal the entire Sea of Tranquility or Mare Tranquilitatis on the moon’s equator near the terminator or sunrise line that makes the moon look like a crescent. The sun is rising right now (morning of the 10th) on the Apollo 11 landing site dubbed Tranquility Base by Neil Armstrong right after landing on July 21st 1969. When showing the moon we are often asked, partly in jest we hope, if they could see the flag left by Armstrong and Aldrin. The answer is no. From the earth, we can barely see anything less than two miles in diameter. It took the Lunar Reconnaissance Orbiter to dip down real low, less than 15 miles altitude, to capture an image of the landing site and what the astronauts left behind. Incidentally the flag was knocked down by the blast of the ascent engine on their lunar module when they took off from the moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon tonight, 9 p.m. September 10, 2013, with the Apollo 11 landing site marked. Created with Virtual Moon Atlas.
Apollo 11 Base from the Lunar Reconnaissance Orbiter. Credit: NASA.
LM is the descent stage of the Lunar Module that served as a launch platform for the ascent stage.
LRRR is the bank of retro reflectors that are still used to reflect earth based lasers to get an extremely accurate range to the Moon.
PSEP is a solar powered instrument package to monitor moonquakes and other information back to Earth after the astronauts had left the Moon.
The flag is not visible about a third of the way between the LM and the camera.
The dark lines are the tracks of the astronauts as they went about their exploration and equipment set up.
