Archive
05/29/2023 – Ephemeris – Sinus Iridium, a hook into night
This is Bob Moler with Ephemeris for Memorial Day, Monday, May 29th. Today the Sun will be up for 15 hours and 16 minutes, setting at 9:18, and it will rise tomorrow at 6:01. The Moon, 2 days past first quarter, will set at 3:41 tomorrow morning.
Let’s look at the Moon tonight. One of my favorite formations is coming into light. It is called Sinus Iridium or Bay of Rainbows. Sorry, there’s no color here. But if caught at right time, and tonight’s the night, this ruined crater will appear as a hook out into night off the upper left edge of the moon. Officially it’s a bay to the Sea of Showers or Mare Imbrium. The north edge of the bay are mountains called the Jura Mountains. The south edge disappears into Mare Imbrium. The floor of the Sinus Iridium is about twelve hundred feet lower than Mare Imbrium. The transition is gradual because it isn’t very noticeable. The formation is large enough to be seen in binoculars. Sinus Iridium is 242 miles wide, a good tenth the diameter of the Moon itself.
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
05/26/2023 – Ephemeris – Sun & Star Party tomorrow at the Sleeping Bear Dunes National Lakeshore
This is Bob Moler with 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 before first quarter, will set at 2:48 tomorrow morning.
Tomorrow, the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society will host a Sun and Star Party at the Dune Climb area of the park. There will be a solar viewing period from 5 pm to about 7 pm. The society has two hydrogen alpha solar telescopes to view the Sun’s chromosphere and prominences. Plus, some members also have solar scopes and white light filtered telescopes to view sunspots on the face of the Sun. Night viewing will start at 9 pm, with the Moon and Venus featured, along with the brighter telescopic wonders of late spring. There will be a pass of the International Space Station from 10:11 to 10:18 pm. The rangers will have an alternate program if it’s cloudy.
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
A Sun Party at the Dune Climb. Credit: Eileen Carlisle.
Preparing to start the May star party, several years ago at the Dune Climb. A few of the telescopes are visible, including the GTAS 25″ “Emmettron” telescope at the far right background. Credit: Eileen Carlisle.
05/25/2023 – Ephemeris – NASA awards contracts for a second lunar lander
This is Ephemeris for Thursday, May 25th. Today the Sun will be up for 15 hours and 9 minutes, setting at 9:14, and it will rise tomorrow at 6:04. The Moon, 2 days before first quarter, will set at 2:26 tomorrow morning.
A week ago, NASA announced that the contract for the second Artemis moon lander would go to a group of companies headed by Blue Origin for 3.4 billion dollars. Unlike Apollo, the rocket that sens crews to the Moon will not contain a moon landing craft. It will be sent out separately before the crew. SpaceX’s Lunar Starship will be used on the first two landings, for Artemis III and IV, while the Blue Origin lander will be used for Artemis V, sometime around 2029 or later. Little detail has been released about the lander, except for an artist’s rendering. It appears to be shorter than the Boeing lander first proposed, which would require an astronaut to climb up and down a very long ladder. SpaceX’s Starship would be taller still, but will have an elevator on the side.
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
NASA picks Bezos’ Blue Origin to build second lunar lander. The crew compartment is on the bottom, allowing for a shorter ladder to the surface. The liquid oxygen (LOX) and hydrogen (LH) tanks are on top. The LH tank is on top with sun shields, with the LOX tank below. I’m guessing here, since very little information has been released. Credit: NASA.
The craft is officially known as the Human Landing System (HLS).
05/23/2023 – Ephemeris – Let’s observe the four-day-old Moon
This is Bob Moler with Ephemeris for Tuesday, May 23rd. Today the Sun will be up for 15 hours and 5 minutes, setting at 9:12, and it will rise tomorrow at 6:06. The Moon, halfway from new to first quarter, will set at 1:25 tomorrow morning.
The four-day-old Moon has uncovered a sea below Mare Crisium or Sea of Crises. It’s Mare Fecunditatis, or the Sea of Fertility. It appears to have been created in the first period of the Moon’s history from 4.55 billion years to 3.92 billion years ago, called the pre- Nectarian geological period, while Mare Crisium is a bit younger, from 3.92 to 3.85 billion years ago, the Nectarian period. Both periods were named for Mare Nectaris, or Sea of Nectar, a small sea next to the Sea of Fertility just coming into sunlight. There are two small, but remarkable craters in the Sea of Fertility called Messier and Messier A which appear to be the result of a double asteroid impact, where it looks like the Moon was struck at a low angle, sending debris out in one direction.
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
4 day old Moon with selected features labeled for May 23, 2023, at 10 pm. Created using Stellarium, LibreOffice Draw and GIMP.
Mare Fecunditatis, 4 day old Moon with the 2 Messier craters labeled. Created using Stellarium, LibreOffice Draw and GIMP.
Messier craters from the Apollo astronauts. Credit NASA.
05/22/2023 – Ephemeris – Exploring the three-day-old Moon
This is Ephemeris for Monday, May 22nd. Today the Sun will be up for 15 hours and 4 minutes, setting at 9:11, and it will rise tomorrow at 6:06. The Moon, 3 days past new, will set at 12:43 tomorrow morning.
Tonight we will see the three-day-old moon low in the west. It may exhibit earthshine. That is, its night side will be illuminated by the Earth’s day side. Just as the earthly night is illuminated by moonlight, especially when the Moon is near full, the night side of the Moon, when near new, is illuminated by earthlight. In binoculars or telescope, the large dark spot, on the Moon’s right edge, is Mare Crisium, or Sea of Crises. The large crater below and a bit left of that sea is Langrenus, named after a 17th century Belgian engineer and mathematician who produced the first lunar map with nomenclature. Langrenus appears as a bright spot as the Sun rises higher for it. Also check out the south end of the cusp of the crescent for a lone mountain peak catching the Sun.
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
An annotated three old Moon as it might appear in binoculars or a small telescope tonight, May 22, 2023, at 10 pm. Click or tap on the image to enlarge it. Created using Stellarium, LibreOffice Draw and GIMP.
05/04/2023 – Ephemeris – The Moon is not quite as dry as we thought
This is Ephemeris for Thursday, May 4th. Today the Sun will be up for 14 hours and 22 minutes, setting at 8:51, and it will rise tomorrow at 6:27. The Moon, 1 day before full, will set at 6:18 tomorrow morning.
The Moon appears to be bone dry. The Apollo astronauts found no rocks with any water in them, or bound to them chemically. However, remote sensing satellites and an infrared flying observatory have detected hints that water does indeed exist on the Moon. Indeed, water would be worth its weight in gold if discovered there. The South Pole of the Moon has permanently shadowed craters which seem to have water ice in them. Recently the, since decommissioned, SOFIA aircraft, sporting an infrared telescope detected water on the daytime side of the Moon, in quantities, to mix units of measurement, 12 ounces of water per cubic meter of soil in the crater Clavius. It’s a large crater in the Southern Hemisphere of the Moon, and incidentally one of my favorite craters.
Also, recently, the Chinese Chang’e 5 lunar sample return mission detected water in the tiny glass beads that were part of the soil it brought back. The beads were the result of meteorite impacts. Maybe NASA might have another look at the lunar soil the Apollo astronauts brought back.
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 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.
Closeup of Clavius from the Lunar Reconnaissance Orbiter. Credit: NASA/LRO.
04/24/2023 – Ephemeris – The reason for the Moon’s phases
This is Bob Moler with Ephemeris for Monday, April 24th. Today the Sun will be up for 13 hours and 55 minutes, setting at 8:38, and it will rise tomorrow at 6:42. The Moon, 3 days before first quarter, will set at 2:02 tomorrow morning.
The Moon’s changing appearance over the month may seem to be mysterious at first glance. Maybe because one may think that the objects in the sky are somehow different from the familiar objects we see around us on the Earth. In ancient times, especially the Greeks, thought that everything in the heavens was perfect and spotless. They explained the definite markings we see as the man-in-the-moon as a reflection of the Earth by a spotless Moon. The Moon’s phases are simply light and shadow on a ball in the sunlight. Sometime, when the Moon appears in the daytime, take a small ball, like a golf ball and hold it up to the Moon, while the ball is also in sunlight, and the small ball will exhibit the same phase as the Moon.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –4 hours). They may be different for your location.
Addendum
This is the best diagram of the Moon’s phases and how the it appears from the Earth. Credit http://planetfacts.org/phases-of-the-moon/ which I recommend.
A demonstration of the Moon’s crescent phase with the styrofoam moon ball we use for Project Astro held up to a light off frame to the right. The line between the bright (day) and dark (night) side of the ball, moon or planet is called the terminator. The night side of the ball is illuminated a bit by the translucency of the ball, and the reflection off my hand. Note the roughness of the ball is visible only at the terminator, where the shadows are longest. I photographed this outside at night to minimize the ball’s nighttime illumination.
02/07/2023 – Ephemeris – A new view on the creation of our Moon
Feb 7. This is Bob Moler with Ephemeris for Tuesday, February 7th. Today the Sun will be up for 10 hours and 5 minutes, setting at 5:59, and it will rise tomorrow at 7:53. The Moon, 2 days past full, will rise at 7:58 this evening.
Is this how the Moon came to be? After the Apollo missions, NASA decided to look at the crust of the Moon which apparently is much like the Earth’s and came up to the conclusion that the Moon was formed by a collision with the Earth by a Mars sized body that they’ve called Thea, named after the mother of the twins Apollo and Artemis. It crashed into the Earth at about a 45-degree angle, and caused a ring of debris around the Earth that would be maintained for a long time. In a newer simulation, the collision could actually create two blobs of material, a large one that became our Moon, in orbit, with about one percent of the Earth’s mass, and a smaller mass that fell back onto 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
A new simulation on how the Moon formed. Credit: PBS.
01/30/2023 – Ephemeris – Two planetary events are happening today
This is Ephemeris for Monday, January 30th. Today the Sun will be up for 9 hours and 44 minutes, setting at 5:48, and it will rise tomorrow at 8:03. The Moon, 2 days past first quarter, will set at 4:34 tomorrow morning.
Today, the planet Mercury was seen as far away from the Sun as it can get for this time of year in the morning sky. It’s called “greatest western elongation”, and it’s distance from the sun and angle is 25 degrees. It’s going to stay pretty close to that for about the next week or so, it’ll be visible if it ever clears up. This is about the latest time one can see Mercury morning elongations this for this time of year. We’re running out of the correct angles for it. This evening, if it’s clear, the planet of Mars will appear near the waxing gibbous Moon. Early on in the evening Mars will be to the upper left of the Moon, which will be approaching it by about its own diameter every hour, until about 1 o’clock in the morning when Mars will it’s closest above the Moon it should be a striking sight.
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
12/08/2022 – Ephemeris – Tonight’s full-ish Moon is near where the June solstice Sun was
This is Ephemeris for Thursday, December 8th. Today the Sun will be up for 8 hours and 54 minutes, setting at 5:02, and it will rise tomorrow at 8:08. The Moon, 1 day past full, will rise at 5:10 this evening.
The bright Moon near full in December rises very high in the south around midnight to 1 am. It is near where the Sun is at the summer solstice. Actually, tonight it is to the lower right of the constellation of Gemini, and to give a topical reference. Tonight, the Moon appears as a soccer ball being kicked by Castor, one of the twins. It’s right off the toe of his foot. In June, the Sun and Full Moon’s positions are reversed. The Sun rises very high in the southern sky at local noon, while the full moon stays low in the south. Or Moon is odd in that respect, Most large satellites of the other planets orbit over their primary’s equator. Our Moon’s orbit is aligned to about 5 degrees off Earth’s own orbit of the Sun, which is angled at 23 and a half degrees from Earth’s equator.
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
The Moon near the summer solstice point overnight tonight at 1:15 am (the 9th). The sky is overlaid with the equatorial grid. The bright blue line that runs just above Orion’s belt is the celestial equator. The declination lines match Earth’s latitude lines are 10 degrees apart. The vertical blue lines are right ascension lines, like earthly longitude lines, and are 15 degrees apart. Each one represents one hour. The orange line is the ecliptic, the path of the Sun in the sky, also the plane of the Earth’s orbit. The red line is the Moon’s orbit, which is inclined by about 5 degrees to the ecliptic. Click on the image to enlarge it. Created using Stellarium and LibreOffice Draw.
Bob Moler's Ephemeris Blog 