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Archive for the ‘The Moon’ Category

11/18/2021 – Ephemeris – An almost total eclipse of the Moon will be visible early tomorrow morning

November 18, 2021 Comments off

This is Ephemeris for Thursday, November 18th. Today the Sun will be up for 9 hours and 27 minutes, setting at 5:11, and it will rise tomorrow at 7:45. The Moon, 1 day before full, will set at 7:58 tomorrow morning.

Should our normal November clouds depart in the early morning hours tomorrow, we will be treated with a very deep partial eclipse of the Moon. At 4:03 am, the Moon will be 97% immersed into the Earth’s inner shadow, with lower left edge peeking out into sunlight. I haven’t heard of any massive volcanic eruptions in our Southern Hemisphere, so the light leaking and bent though the Earth’s atmosphere from all the simultaneous sunrises and sunsets during the eclipse won’t be too diminished and give us a coppery hue in the shadow. The shadow will touch the Moon at its top edge at 2:19 am. The maximum will occur at 4:03 am, and the last bit of the shadow will depart at the lower right edge of the Moon at 5:47 am.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Partial Lunar Eclipse 11/19/21 4:05 EST maximum

November 19, 2021, partial lunar eclipse maximum at 4:05 am EST. Orientation of the Moon and shadow could be different if not viewing from Northern Michigan. Created using Stellarium.

Lunar Eclipse Diagram

Lunar Eclipse Diagram for November 19, 2021. Effects of the eclipse on the Moon at P1 and P4 are not visible. U1 is the Moon at the beginning of the partial eclipse. U4 is the Moon at the end of the partial eclipse. A duskiness on the Moon’s face on the side closest to the umbral shadow will be visible just before and after the partial eclipse. Note that this diagram is not at the same orientation that an observer might experience. Created from a NASA PDF document on the NASA Eclipse Website. https://eclipse.gsfc.nasa.gov/eclipse.html.

11/16/2021 – Ephemeris – How China retrieved a sample from the Moon, and what Chang’e 5 is up to next

November 16, 2021 Comments off

This is Ephemeris for Tuesday, November 16th. Today the Sun will be up for 9 hours and 31 minutes, setting at 5:13, and it will rise tomorrow at 7:42. The Moon, 3 days before full, will set at 5:49 tomorrow morning.

China’s Chang’e sample return mission of late last year was quite a feat. The spacecraft had an orbiter that orbited the Moon, and sent a lander with an ascent rocket. After the lander secured its samples, it put them in the ascent rocket, which launched back up to the orbiter. The samples were placed in a reentry capsule attached to the orbiter, which left the Moon’s orbit and headed back to the Earth. Near Earth, it ejected the reentry capsule and swung past Earth and headed out to the Earth-Sun Lagrangian point 1 between the Earth and Sun. There are already several satellites in halo orbits around L1, because it’s a great spot to be to study the Sun unobstructed by the Earth, and detect Coronal Mass Ejections (CMEs) about an hour before they reach Earth. NASA, NOAA and the European Space Agency all have satellites out there.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Chang'e 5 Descent Capsule

Chang’e 5 Descent Capsule lands. It looks like a miniature Russian Soyuz Descent capsule. Credit Chinese Space Agency via Global Times.

Earth-Sun Lagrangian Points

Earth-Sun Lagrangian Points. These are where a small body can stay. L1, 2 and 3 are unstable, so some little effort is needed to keep a spacecraft near there. L4 and L5 are stable. Source: Wikimedia Commons, Xander89. Click to enlarge.

1/15/2021 – Ephemeris – What the Chinese Chang’e 5 lunar mission found

November 15, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, November 15th. Today the Sun will be up for 9 hours and 34 minutes, setting at 5:14, and it will rise tomorrow at 7:41. The Moon, halfway from first quarter to full, will set at 4:45 tomorrow morning. | Late last year, the Chinese sent an uncrewed spacecraft to the Moon to collect samples of the surface material. That material is called regolith, and they drilled down at least a meter, which they returned to the Earth. An international team of geologists has been studying the material, and we have the first reports. Apparently the material they picked up was dated at 2 billion years, which is an intermediate age to the material picked up by the Apollo missions that dates either 3 billion years or older or 1 billion years. That helps fill gaps in the Moon’s history. Of course, all the material in the solar system is 4.5 billion years old. But the radioactive dating clock is reset when a rock is melted and solidifies.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Chang'e 5 Landing-Site on full moon map

Chang’e 5 Landing-Site on full moon map. Created using Virtual Mon Atlas.

11/12/2021 – Ephemeris – The Moon appears to wobble slowly over the month

November 12, 2021 Comments off

This is Ephemeris for Friday, November 12th. Today the Sun will be up for 9 hours and 41 minutes, setting at 5:17, and it will rise tomorrow at 7:37. The Moon, 1 day past first quarter, will set at 1:27 tomorrow morning.

When I look at the Moon, I check the position of one particular feature. A small, nearly circular gray area near the right or western edge of the Moon’s disk. It’s called the Sea of Crises, or in Latin, Mare Crisium. The reason I check it is that over the month its distance from the edge, or what astronomers call the limb, changes. That sea is about as far as it can get from the limb now. The reason for this wobbling back and forth, called libration, is that the Moon rotates at a constant rate due to angular momentum, but its revolution around the earth is an ellipse, so it doesn’t move with a uniform speed in its orbit. It moves faster at its closest to the Earth, called perigee, and is slowest at apogee, its farthest from the Earth.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum.

Moon tonight libration

The Moon tonight (November 12, 2021) showing Mare Crisium (Sea of Crises) about as far from the limb (Moon’s edge) as it can get. Created using Stellarium.

Moon's libration animation

Simulation of the Moon’s phase and libration for October 2007 by Tomruen. Image is in the Public Domain.

09/20/2021 – Ephemeris – The Harvest Moon rises tonight

September 20, 2021 Comments off

This is Ephemeris for Monday, September 20th. Today the Sun will be up for 12 hours and 15 minutes, setting at 7:43, and it will rise tomorrow at 7:29. The Moon, at full today, will rise at 8:03 this evening.

Tonight’s full moon is the Harvest Moon. It is the most famous of the named full moons, and was very useful in the days before electric lights. The reason is that the Moon, around the time it is full now, doesn’t advance its rising time very much from night to night, effectively extending the light of twilight to allow more time to gather in crops. This is because the Moon is moving north as well as eastward. The farther north it is, the longer it stays up and retards the advance in rise times. On average, the Moon rises 50 minutes later each night. This week, the interval is down near 20 minutes advance in moonrise times per day, extending twilight and the time each day to harvest the crops for a few more days.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4 hr). They may be different for your location.

Addendum

Autumn vs spring sunset ecliptic

The autumn vs spring sunset ecliptic. I’m using the autumnal equinox 2021, with the tip of the spout of the Sagittarius Teapot at due south, and vernal equinox 2022, with the red star Betelgeuse in Orion at due south as examples. Click on the image to enlarge it. Created using Stellarium and GIMP.

The ecliptic for the autumnal equinox runs low in the south, a preview of the Sun’s apparent travel for the next six months of fall and winter. Besides the planets, the Moon at sticks close to that line, as do the planets. The full moon rising in the east as the Sun sets does so at a shallow angle, so for a week or so around the full moon, its advance in rise times can be as little as 20 minutes per night. In spring, it can be much longer than an hour.

09/17/2021 – Ephemeris – The Moon has an atmosphere of sorts; Plus, I capture Inspiration 4 passing overhead

September 17, 2021 Comments off

This is Ephemeris for Friday, September 17th. Today the Sun will be up for 12 hours and 24 minutes, setting at 7:49, and it will rise tomorrow at 7:25. The Moon, 3 days before full, will set at 4:24 tomorrow morning.

Jupiter, tonight, will be above the Moon. Everyone knows that the Moon is airless, that is has no atmosphere. That is not strictly true. Apollo astronauts saw glows and crepuscular rays in the direction of the Sun before its rising an after it set as they orbited the Moon. In 2013 NASA sent an orbiter spacecraft named LADEE to the Moon to investigate. LADEE stands for Lunar Atmosphere and Dust Environment Explorer. It orbited low over the Moon’s equator. The atmosphere of the Moon consists of some gasses like sodium, neon, argon and helium plus dust electrostatically charged by the Sun’s x-ray and ultraviolet emissions and sent aloft, up to many kilometers. The dust will fall back down, but the gasses will be dissipated by the solar wind. It’s very tenuous.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addenda

Jupiter, Saturn and the Moon tonight at 9 pm tonight, September 17, 2021. Jupiter will be moving to be directly below Jupiter by one in the morning. Created using Stellarium.

Apollo 17 twilight ray sketches

Apollo 17 twilight ray sketches. Credit: NASA/Apollo 17 Astronauts.

LASDEE

Artist’s depiction of LADEE in orbit of the Moon. Courtesy NASA.

Inspiration 4 spacecraft caught flying over Northern Michigan

Inspiration 4 spacecraft passing through Hercules

The thin vertical streak on the left side of the image is the Inspiration 4 spacecraft against the stars of Hercules in a 15 second exposure with a Canon Rebel T5 camera, f/3.5, ISO 6400, 18 mm fl. The famous Keystone of Hercules asterism is to the upper right of center. It’s a bit out of focus due to my problem seeing the screen at a high angle. (Getting old). It was quite dim, so I actually couldn’t see it in the moonlight. Credit: mine.

I was guided to the time and place in the sky by heavens-above.com

09/14/2021 – Ephemeris – Lack of spacesuits just one of Artemis problems of getting humans back to the Moon

September 14, 2021 Comments off

This is Ephemeris for Tuesday, September 14th. Today the Sun will be up for 12 hours and 33 minutes, setting at 7:54, and it will rise tomorrow at 7:21. The Moon, 1 day past first quarter, will set at 12:53 tomorrow morning.

The bright gibbous Moon is a feast for binoculars or a telescope. However, the speed-up plan to land crews on the Moon in 2024 proposed by the former President is not appearing to pan out. One major item is space suits, which must be more rugged and impervious to the Lunar regolith, or soil, whose grains are tiny, angular and sharp, and get into everything, and can destroy spacesuit joints. NASA has been working on them for 14 years, and by itself could cost a billion dollars. They might be ready by 2025. Besides delays to the SLS rocket, the contract with SpaceX to furnish a lunar lander is now tied up in litigation by one of the contract losers. NASA’s trying to land humans on the Moon on one half of one percent of the Federal budget, plus do everything else it does.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Prototype lunar spacesuit

Prototype lunar spacesuit. xEMU stands for Exploration Extravehicular Activity Mobility Unit. Of course. This uncredited image is from slashgear.com in 2019, so I wouldn’t believe the date. These xEMU suits may eventually cost a billion dollars to develop and produce. Click on the image to enlarge it.

09/13/2021 – Ephemeris – The Greeks knew the size and shape of the Earth and estimated the distance to the Moon a long time ago

September 13, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, September 13th. Today the Sun will be up for 12 hours and 37 minutes, setting at 7:56, and it will rise tomorrow at 7:20. The Moon, at first quarter today, will set at 11:57 this evening.

The Ancient Greeks used lunar eclipses to determine that Earth is a sphere, and worked on determining the distance to the Moon. From ancient times, the Greeks knew that an eclipse of the Moon was caused by the Earth’s shadow falling on the Moon. Since the Earth’s shadow was always circular, no matter where the Moon was in the sky during an eclipse, the Earth must be a sphere since that’s the only three-dimensional body that always casts a circular shadow. They also used the size of the Earth’s shadow to estimate the distance to the Moon. The lunar distance, on average, is 60.8 times the Earth’s radius away. The first estimates were about one third of that. Hipparchus in the 2nd century BC got much closer. It got even better from there.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Partial Lunar Eclipse showing arc of the Earth's shadow

Partial Lunar Eclipse showing circular arc of the Earth’s shadow. Taken 04:15 UT August 17, 1970. Credit: the author.

The size of the Earth was unknown until Eratosthenes did in 240 BC. He came up with the circumference of the Earth to a fairly high degree. The Circumference is equal to the radius of a sphere or circle by 2πr.

08/23/2021 – Ephemeris – Seeking shelter on the Moon

August 23, 2021 Comments off

This is Ephemeris for Monday, August 23rd. Today the Sun will be up for 13 hours and 39 minutes, setting at 8:34, and it will rise tomorrow at 6:56. The Moon, 1 day past full, will rise at 9:39 this evening.

The area of interest on the Moon for NASA’s Artemis crewed landing program and the target for Chinese lunar ambitions is the south pole, where signs of water ice have been detected in permanently shadowed craters. That is a valuable resource, if one wants to live off the land on the Moon. There’s another resource that is also valuable in finding: shelter from radiation and the Moon’s extreme temperature swings. Those are lava tubes. They are lava channels in which lava flowed, the top and sides cooled and crusted over. They emptied when the lava ran out, leaving a hollow tube. Sometimes part of the upper crust fails, leaving what is called a skylight. Several of these skylights have been found on the Moon and even Mars.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Lunar lava tube skylight

A skylight betrays the presence of a lunar lava tube. Credit NASA/LRO.

Lava tube in Hawai'i

Here’s an earthly lava tube on the Island of Hawai’i, I visited in 2012 with my wife. It was on the site of a coffee plantation south of Kona. Credit mine.

08/20/2021 – Ephemeris – The Moon will pass Saturn tonight

August 20, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, August 20th. Today the Sun will be up for 13 hours and 48 minutes, setting at 8:39, and it will rise tomorrow at 6:52. The Moon, 2 days before full, will set at 5:26 tomorrow morning.

The Moon is passing Saturn this evening. Saturn will be directly above the Moon by about 10 moon-widths or five degrees at 10 pm tonight. Tomorrow night the Moon will have moved toward Jupiter, which at the same time of night, the planet will appear to the upper left of our satellite. The sky appears to us to be a dome over us, which is useful for imagining the constellations, navigation, and pointing telescopes. However, that is an illusion. The night sky is impossibly and wonderfully deep. The Moon is a quarter of a million miles away, Jupiter and Saturn are hundreds of million miles away. The nearest nighttime stars are trillions of miles away, and so on as far as our eyes and instruments can see.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Moon passing Saturn animation

Animation showing the Moon passing Saturn and Jupiter at 10 pm on August 20 & 21, 2021. Beside the Moon jumping position between the two dates, the planets and stars do too, but to a lesser extent to the right. This is due to the Earth’s change in position as it orbits the Sun. Stars rise and set 3 minutes, 56 seconds earlier each night. The Created using Stellarium and GIMP.