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05/09/2022 – Ephemeris – Monday’s Moon

May 9, 2022 Comments off

This is Bob Moler with Ephemeris for Monday, May 9th. Today the Sun will be up for 14 hours and 35 minutes, setting at 8:57, and it will rise tomorrow at 6:20. The Moon, 1 day past first quarter, will set at 4:03 tomorrow morning.

Nothing is more fun than to look at the Moon through binoculars or a small telescope around its first quarter phase. The little gray oval on the face of the Moon on its upper right, not connected to all the other gray areas, is called the Sea of Crises or Mare Crisium. I use Mare Crisium as a telltale for the Moon’s libration or wobble. Tonight Crisium is close to the edge of the Moon, so on a day after first quarter, we’re seeing somewhat more territory on the left side of the Moon than we normally would at this phase. At the bottom or south end of the Moon are two prominent craters visible even in binoculars, the small but distinct Tycho, and the much larger Clavius, whose floor contains other craters and is convex following the curvature of the Moon.

Reminder: There will be a total lunar eclipse occurring a week from this morning, actually starting Sunday evening Eastern Daylight Time. I’ll give you full details later in the week. That’s the evening of May 15th, through morning of the 16th.

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

Addendum

8-day old Moon

The 8-day-old Moon labeled via animated GIF, as it would appear in binoculars or a small telescope tonight, May 9, 2022. Created using Virtual Moon Atlas, GIMP and LibreOffice Draw.

Translations

Mare Crisium – Sea of Crises
Mare Fecunditatis – Sea of Fertility
Mare Frigoris – Sea of Cold
Mare Imbrium – Sea of Showers
Mare Nectaris – Sea of Nectar
Mare Nubium – Sea of Clouds
Mare Serenitatis – Sea of Serenity
Mare Tranquillitatis – Sea of Tranquility
Sinus Medii – Bay of the Center

Note that Mare is pronounced Mar-é

04/22/2022 – Ephemeris – Earth Day and the Moon passes four planets in the morning

April 22, 2022 Comments off

This is Ephemeris for Earth Day, Friday, April 22nd. Today the Sun will be up for 13 hours and 50 minutes, setting at 8:36, and it will rise tomorrow at 6:45. The Moon, 1 day before last quarter, will rise at 3:43 tomorrow morning.

The Lyrid meteor shower will still be active tonight and tomorrow morning from 10 pm to almost 4 am. Speaking of things hitting the Earth, NASA’s DART Mission to collide and deflect a small asteroid is still on its way to smash into a tiny asteroid in September to see how it works. A more predictable disaster is climate change or global warming, which is continuing to appear more rapid than earlier thought. It demands that nations start immediately to reduce carbon emissions to slow and eventually stop the rise in global temperatures. As someone said: “There is no Planet B”. Mars isn’t it. It’s too cold, too small, too dry, and the air is too thin and contains no free oxygen. So support your local planet, it’s the only one we’ve got.

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

Addendum

There is an interesting Planet and morning planet encounter Sunday through Wednesday mornings as the Moon passes four planets.

The Moon passing the morning planets from Sunday to Wednesday mornings 4/24 to 4/27/2022

The Moon passing the morning planets from Sunday to Wednesday mornings 4/24 to 4/27/2022. Note also the approach of Jupiter and Venus. Their paths will cross on Saturday, 4/30/2022. Click on the image to enlarge it. Created using Stellarium and GIMP

04/14/2022 – Ephemeris – The Moon appears to wobble

April 14, 2022 Comments off

This is Bob Moler with Ephemeris for Thursday, April 14th. Today the Sun will be up for 13 hours and 26 minutes, setting at 8:26, and it will rise tomorrow at 6:58. The Moon, 2 days before full, will set at 6:43 tomorrow morning.

Tonight’s Moon is nearly full, only two days to go. In the evening, the little dark sea on the Moon called Mare Crisium or Sea of Crises is near the top of the Moon. Now it’s real close to the top edge of the Moon, what astronomers call the limb. Ten days ago, when the Moon was a crescent, Mare Crisium was farther from the limb. This wobbling motion over the lunar month is called libration. This occurs because the Moon has an elliptical orbit of the Earth and speeds up when it’s closer and slows when it’s farther away. However, the Moon’s rotation is constant due to its angular momentum. The period of the revolution of the Moon around the Earth exactly matches its rotation. When the Moon is farthest, its rotation gets a bit ahead of its revolution around the Earth. When closest, the rotation lags a bit. So it appears to wobble over the lunar month.

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

Addendum

The Moon as it should appear at 10 pm tonight

The Moon as it should appear at 10 pm tonight, April 14, 2022. Note the position, relative to the Moon’s limb, of the small lunar sea called Mare Crisium near the top of the Moon. Mare Crisium means Sea of Crises. It is quite close to the limb tonight. In the animation below, shown without the phase, the orientation of the Moon is not changed by the position in the sky or the latitude of the observer. Created using Stellarium.

Demonstration of libration via animation

A demonstration of libration by viewing the position of Mare Crisium. Also note that there is also a libration in the Moon’s latitude, causing a north-south nodding. Another good indicator of libration is the dark floored crater called Grimaldi on the left side of the Moon, which is not visible tonight in the image at the top. But it will appear in sunlight tomorrow night. Created using Virtual Moon Atlas.

04/08/2022 – Ephemeris – Landing a spacecraft at the Moon’s South Pole will be a tricky prospect

April 8, 2022 Comments off

This is Ephemeris for Friday, April 8th. Today the Sun will be up for 13 hours and 8 minutes, setting at 8:19, and it will rise tomorrow at 7:09. The Moon, 1 day before first quarter, will set at 3:58 tomorrow morning.

The Artemis missions are to land near the South Pole of the Moon. Unlike the Earth’s 23 and a half degree axial tilt the Moon’s is only a degree and a half, so there is little month long variation of the Sun angle, though the Sun’s direction along the horizon revolves 360 degrees over 29 and a half days, the length of its orbit of the Earth. It should make for quite a challenge to land the human lander safely near the lunar South Pole. The lander has to choose a spot in sunlight to land that’s relatively smooth. The reason for the attraction of the lunar South Pole is the presence of water ice in permanently shadowed craters near and at the pole. The Moon’s North Pole isn’t as heavily cratered, with fewer permanently shadowed craters.

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

Addendum

Lunar South Pole Flyover area w-south pole

Lunar South Pole Flyover area with approximate South Pole marked based on Virtual Moon Atlas. Did you note a theme in some crater names? Click on the image to enlarge it. Credit: NASA/LRO.

South pole ice

The South Pole of the Moon, where the presence of water ice is detected by the absorption of neutrons by the hydrogen atoms in the ice. Credit NASA/GSFC/SVS/Roscosmos.

03/11/2022 – Ephemeris – Looking at the northern part of the Moon and the crater Plato

March 11, 2022 Comments off

This is Ephemeris for Friday, March 11th. Today the Sun will be up for 11 hours and 41 minutes, setting at 6:43, and it will rise tomorrow at 7:00. The Moon, 1 day past first quarter, will set at 4:18 tomorrow morning.

As the Moon moves around the Earth, now one day past first quarter, more of it is revealed in sunlight. The top or north part of the moon is of interest now. The second-largest lunar sea, Mare Imbrium, or Sea of Showers, is now half illuminated by the advancing terminator, the sunrise line. That can be seen with the naked eye. With binoculars, in the mountains north or above Imbrium can be found the flat floored crater or walled plain called Plato. This crater is situated in the lunar Alps. Mountains on the Moon are named after their earthly counterparts. Visible in telescopes now will be the Alpine Valley cutting through the Alps just to the right of Plato. Each night from new to full, more of the Moon’s features are revealed near the terminator.

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 first quarter plus 1 day hilighting Plato

The Moon tonight, a day past first quarter, March 11, 2022, outlining the Mare Imbrium, crater Plato area, which is seen in detail below. Created using Virtual Lunar Atlas.

The Crater Plato and the Alps

The Moon tonight, March 11, 2022, highlighting the crater Plato and lunar Alps. The Alpine Valley (Vallis Alpes), lies under the caption “Alpes” for the mountains. One of cool things to watch when the terminator is situated just right is to watch the shadows of the mountains retreat across Plato’s crater floor as the Sun rises. The shadows of the peaks appear very jagged as they retreat. Created using Virtual Lunar Atlas.

03/10/2022 – Ephemeris – Viewing the Moon at first quarter tonight

March 10, 2022 Comments off

This is Ephemeris for Thursday, March 10th. Today the Sun will be up for 11 hours and 38 minutes, setting at 6:42, and it will rise tomorrow at 7:02. The Moon, at first quarter today, will set at 3:26 tomorrow morning.

By the time we spot the moon this evening, it will be over half a day from being exactly first quarter phase. Looking at the brighter part of the Moon in binoculars, which is at the bottom or south end. We are looking at the lunar highlands of mostly very old craters that extend back to the formation of the Moon, nearly 4.5 billion years ago, that weren’t obliterated by the asteroid strikes that created the darker maria or lunar seas half a billion years later. In small telescopes there is a vertical line of three large craters whose names, from largest to smallest and top down, are Ptolemaeus, Alphonsus, and Arzachel. Alphonsus is a curious crater. In 1958 a Soviet astronomer recorded a possible volcanic eruption or outgassing from the crater floor.

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

Lunar craters Ptolemaeus Alphonsus Arzachel Outlined

Lunar craters Ptolemaeus, Alphonsus and Arzachel outlined on the Moon’s disk, at first quarter, at 8 pm, March 10, 2022. Created using Virtual Moon Atlas.

Closeup of lunar craters Ptolemaeus, Alphonsus and Arzachel

Closeup of lunar craters Ptolemaeus, Alphonsus and Arzachel, with other nearby craters, outlined above. Created using Virtual Moon Atlas.

02/15/2022 – Ephemeris – The Moon’s splashiest crater

February 15, 2022 Comments off

This is Ephemeris for Tuesday, February 15th. Today the Sun will be up for 10 hours and 28 minutes, setting at 6:11, and it will rise tomorrow at 7:41. The Moon, 1 day before full, will set at 8:09 tomorrow morning.

The Moon at 8 pm tonight will be only 16 hours before being full. As down as I am about full moons due to the fact that they light up the sky and flood out the dimmer objects, I once in a while stop and view it. Being less than a day from full, we see it tonight from very nearly the direction of the Sun, so there will be few shadows to be had. The crater Tycho is near the bottom or south end of the moon and has long rays of tiny ejecta craters. The full moon is the best time to see these rays, which are easily visible in binoculars, through which Tycho itself looks like a bright dot. In telescopes, Tycho looks like a small, bright crater with a dark ring around it. The full moon is super bright. It’s daytime over 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

Tycho's rays at full moon

An image I took of the full moon in August 2016 and processed for maximum contrast to show the crater Tycho with its dark ring, near the bottom (south) of the Moon and its rays that stretch for hundreds of miles across the face of the Moon. The image is fairly low resolution, taken with a 300 mm telephoto lens. Click on the image to enlarge it a bit.

02/11/2022 – Ephemeris – The Sun Rises on the Moon’s Bay of Rainbows

February 11, 2022 Comments off

This is Ephemeris for Friday, February 11th. Today the Sun will be up for 10 hours and 16 minutes, setting at 6:05, and it will rise tomorrow at 7:47. The Moon, 3 days past first quarter, will set at 5:34 tomorrow morning.

On the moon tonight, the gibbous phase and the terminator on the left side of the moon is revealing a large semicircular mountain range called the Jura Mountains that encloses a flat lava plain that looks like a bay in the margin of the Sea of Showers or Mare Imbrium. It is easily visible in binoculars this evening, when the sunrise line is crossing the bay. The Jura Mountains will appear as a hook out of the upper left edge of the moon. That’s about the coolest sight that’s visible on the moon that can be seen with binoculars. It’s especially striking if seen in a small telescope.

Also, related to the Moon: The Artemis-1 uncrewed mission to orbit the Moon has been pushed off at least one month or more, to this April or even May.

Addendum

Sunrise at Sinus Iridium, full Moon disc

Sunrise at Sinus Iridium, full Moon disc with annotations. Click on the image to enlarge it. Moon image created using Stellarium.

02/10/2022 – Ephemeris – The waxing gibbous Moon is revealing more seas and craters

February 10, 2022 Comments off

This is Ephemeris for Thursday, February 10th. Today the Sun will be up for 10 hours and 14 minutes, setting at 6:04, and it will rise tomorrow at 7:48. The Moon, 2 days past first quarter, will set at 4:38 tomorrow morning.

The Moon tonight is a waxing gibbous phase. More gray lunar seas are appearing near the terminator, the sunrise line. From north to south these seas, most only partially in sunlight, are: At the far north, the Cold Sea, Sea of Showers, The sea where the famous crater Copernicus is, the Sea of Islands. The southernmost sea at the terminator is the Sea of Clouds. Some large and prominent craters can be seen with binoculars or a small telescope can be seen in the south, the striking and relatively fresh Tycho, with its Moon girdling ejecta rays, though the rays are best seen at full moon. And the huge crater Clavius, with an arc of 5 smaller craters, one on its wall and the others on its floor, in ever diminishing sizes.

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

2 days past first quarter Moon annotated

2 days past first quarter Moon as it would be seen in a small telescope or even binoculars, annotated. For this evening, February 10, 2022. Click on the image to enlarge it. Created using Virtual Moon Atlas. Annotations in white are from the app, mine are in green. Translations of the sea names are below.

Translations

Mare Crisium – Sea of Crises
Mare Fecunditatis – Sea of Fertility
Mare Frigoris – Sea of Cold
Mare Imbrium – Sea of Showers
Mare Insularum – Sea of Islands
Mare Nectaris – Sea of Nectar
Mare Nubium – Sea of Clouds
Mare Serenitatis – Sea of Serenity
Mare Tranquilitatis – Sea of Tranquility

A closer look

Clavius

A montage of Clavius as photographed by one of the Lunar Orbiter spacecraft in the 1960s From Digital Lunar Orbital Photographic Atlas. Credit Jeff Gillis, Lunar and Planetary Institute.

02/08/2022 – Ephemeris – The first quarter Moon tonight

February 8, 2022 Comments off

This is Ephemeris for Tuesday, February 8th. Today the Sun will be up for 10 hours and 8 minutes, setting at 6:01, and it will rise tomorrow at 7:51. The Moon, at first quarter today, will set at 2:34 tomorrow morning.

The Moon tonight, will be about 12 hours past being exactly first quarter, so it will be showing to be just a bit gibbous, that is a bit more than 50% illuminated by the Sun from our vantage point. In binoculars, the gray lunar seas, which are actually frozen lava filled plains, dominate the upper right quarter of the Moon. At the bottom, or south end of the Moon are the lighter more cratered region of the Moon called the Lunar Highlands. It is near the terminator, the line between day and night on the Moon, where shadows are longest, where craters can be seen by the shadows of the rims. Farther away from the terminator, the Sun is higher in the Moon’s sky, so the shadows get shorter or disappear all together.

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

Hours after first quarter moon

The is what the Moon might look like tonight, hours after first quarter. Just a bit of Mare Imbrium (Sea of Showers) is visible. Mare Serenitatis is the Sea of Serenity, Mare Tranquilitatis is the Sea of Tranquility. The green annotation is mine. BTW, Mare is pronounced Mar-e. It’s Latin, meaning sea. Created using Virtual Moon Atlas, a free app that can be downloaded from a link on the right, or listed under Free Astronomical Software.