08/15/2022 – Ephemeris – Saturn moves into the evening sky

This is Ephemeris for Monday, August 15th. Today the Sun will be up for 14 hours and 3 minutes, setting at 8:48, and it will rise tomorrow at 6:46. The Moon, halfway from full to last quarter, will rise at 10:55 this evening.

Yesterday, Saturn was in opposition to the Sun. I’m not implying an argument here. Opposition is when a planet is opposite the Sun in the sky, so it rises around sunset and sets around sunrise. That means Saturn is the closest it can get to us this year. For the record, that’s 836 million miles (1,345 million kilometers). Saturn will first appear tonight in the southeast when it gets dark enough, say around 9:15 to 9:30 pm. It is in the constellation of Aquarius now. It is moving northeastward in our skies, or it would if it weren’t at opposition, and moving backward or retrograde as the Earth is, in effect, lapping Saturn in our eternal race around the Sun. Saturn’s rings appear to slowly get skinnier as the planet moves to an equinox, where its rings, which orbit its equator, will tilt edgewise to the Sun, and the Earth in 2025.

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

Display of the solar system out to Saturn, with added line showing Saturn’s location opposite the Sun from the Earth. This make the Earth nearly in line from the Sun to Saturn. This is the time that Saturn would be closest to the Earth. Credit: my LookingUp app. I wanted to use NASA’s Eyes, but there were too many interplanetary spacecraft near the Earth. The Earth was crowded out by spacecraft labels.

How the appearance of the rings change as Saturn orbits the Sun. Credit: NASA Hubble.

08/12/2022 – Ephemeris – The Perseid meteor shower reached its peak tonight with a bright moon

This is Ephemeris for Friday, August 12th. Today the Sun will be up for 14 hours and 11 minutes, setting at 8:53, and it will rise tomorrow at 6:42. The Moon, 1 day past full, will rise at 9:48 this evening.

The Perseid meteor shower will reach its peak tonight as the nearly full Moon rises. Only the brightest of these meteors will be visible in the bright moonlit sky. Next year the Moon will be less bright and will only interfere in the early morning hours. Comet Swift-Tuttle is responsible for shedding the tiny bits of rock that end up orbiting the Sun near its path. The Earth plows through these particles every year at this time, giving us a great sky show, which at peak on a dark morning provide 60 or more of these so-called shooting stars per hour. The members of the Perseids will all seem to come from the northeastern sky, from the top of the constellation of Perseus the hero. The star figure to me instead looks like the cartoon roadrunner running up the sky.

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

Perseid fireballs in one of NASA’s all sky cameras during the morning hours of August 13, 2017. This is a long time exposure. The bright swath in the image is the Moon that morning. Since it is a time exposure, the radiant is also moving with the earth’s rotation, so the meteors only seem to come from the northeastern sky. North is at the top, and East is to the left. The Moon that morning was 1 day before last quarter, so tonight’s Moon will be even brighter. Credit NASA.

Screen capture of an interactive animation of the orbits of the Perseid meteoroids and the inner planets. The planets move counterclockwise, while the meteoroids move clockwise and cross the Earth’s orbital plane at a high angle. Image taken from the International Meteor Organization, imo.net. Interactive animation by MeteorShowers.org.

08/11/2022 – Ephemeris – Another lunar mission in support of Artemis

This is Ephemeris for Thursday, August 11th. Today the Sun will be up for 14 hours and 14 minutes, setting at 8:54, and it will rise tomorrow at 6:41. The Moon, at full today, the full Sturgeon Moon, and a supermoon to boot, will rise at 9:18 this evening.

As we await the opening of the Artemis 1 launch window in two and a half weeks, and a successful mission, Artemis 2 may launch as early as May of next year with a crew of four for a loop around the Moon on a free return trajectory back to the Earth. They will not stay in orbit of the Moon. South Korea’s Pathfinder Lunar Orbiter was launched a week ago on a long trajectory to reach the Moon in December. Among other things, it has a NASA supplied camera to photograph the floors of the permanently shadowed craters at the Moon’s South Pole, a prime target for the Artemis missions. The pace of lunar missions by NASA’s partners is increasing, looking to a crewed landing, possibly as early as 2025 or 2026.

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

Artist’s vision of the Korea Pathfinder Lunar Orbiter “Danuri” communicating from the Moon. It has instruments to photograph the Moon, and otherwise detect resources. It also contains a NASA supplied ShadowCam. Credit: KARI, Korea Aerospace Research Institute.

ShadowCam operation imaging the floors of permanently shadowed craters. The camera is 800 times more sensitive than those on the Lunar Reconnaissance Orbiter. Credit NASA.

 

08/10/2022 – Ephemeris – Let’s search for the naked-eye planets for this week

This is Bob Moler with Ephemeris for Wednesday, August 10th. Today the Sun will be up for 14 hours and 16 minutes, setting at 8:56, and it will rise tomorrow at 6:40. The Moon, 1 day before full, will set at 5:37 tomorrow morning.

Let’s search for the naked-eye planets for this week. All but one of the naked-eye planets are in the morning sky, That one is Mercury, too close to the Sun to be seen in the evening. At 6 am tomorrow, the planets will be spread out from brilliant Venus low in the east-northeast to Saturn in the west-southwest. Mars will be a lot higher than Venus in the southeast. Jupiter is farther to the right in the south-southwest. Mars is dimmer than Jupiter, but is slowly getting brighter as the Earth creeps up on it. Saturn ends the line of planets much lower than Venus in the west-southwest. Tonight, Saturn will rise about 9:12 pm in the east-southeast. It won’t be in the morning sky next week, having moved into the evening sky.

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

Saturn and the Moon at 10 in the evening. Saturn is not officially in the evening sky, but it rises shortly after sunset. Created using Stellarium.

The Moon tonight with animated labels for 10 pm, August 10, 2022. Created using Stellarium; Labels, LibreOffice Draw, animation, GIMP.

Morning planets at 6 am tomorrow morning, August 11, 2022. With six weeks left in summer, the bright winter stars begin to appear in morning twilight, along with the planets. Click on the image to enlarge it. The span of the planets from Venus to Saturn is 158 degrees. Click on the image to enlarge it. Created using Stellarium.

Views of Saturn, Jupiter, and Venus (north up) as they would be seen in a small telescope, with the same magnification. Saturn is shown at 10 pm EDT (UT -4) on August 10, 2022. Jupiter and Venus are shown for, tomorrow morning at 6 am. I do not show planets less than 10 seconds of arc in diameter. Apparent diameters: Saturn 18.76″, its rings 43.70″; Jupiter 46.47″. Mars is not shown, its apparent diameter is 8.71″, 84.7% illuminated; Venus 10.46″, 94.3% illuminated. Jupiter’s moon Europa is in the planet’s shadow at that time. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on August 10, 2022. The night ends on the left with sunrise on the 11th. Notice that all the naked-eye planets except Mercury are in the morning sky now. That’s about to change in a week and a half, when Saturn moves into the evening sky at opposition on the 14th. Click on the image to enlarge it. Created using my LookingUp program.

08/09/2022 – Ephemeris – Artemis I mission could launch by the end of the month

This is Bob Moler with Ephemeris for Tuesday, August 9th. Today the Sun will be up for 14 hours and 19 minutes, setting at 8:57, and it will rise tomorrow at 6:39. The Moon, 2 days before full, will set at 4:15 tomorrow morning.

NASA has announced the launch date for the Artemis 1 uncrewed mission to the Moon. It’s August 29th. Or, in NASAspeak, NET (not earlier than) August 29th. Being the first launch of a new vehicle, they probably won’t launch on that day, due to encountered problems. Their second wet dress rehearsal still fell a few seconds short of the programmed end time, just before the main engines would be lit. If Artemis can’t launch on the 29th, the next date to go will be September 2nd, The four-day wait is because in that period the Orion capsule would spend too much time in the Earth’s shadow and without sunlight for its solar panels, depleting its batteries, on its way out to the Moon. The next opportunity after that would come on the 5th. Then a long wait til the 20th.

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

Simulated Artemis launch from Launch Pad 39B as it would be seen from offshore. Credit NASA.

Major mission milestones. Click on the image to enlarge. Credit: NASA

Ephemeris Extra – Wandering through Sagittarius

Sagittarius in a short time exposure with added annotations. The “M” designations are objects in Charles Messier’s catalog created in the latter half of the 18th century. LSSC is the Large Sagittarius Star Cloud, SSSC is the Small Sagittarius Star Cloud. Credit Bob Moler.

Sagittarius is seen low in the south in August. It’s between Scorpius to the west, and Capricornus, rising in the southeast. The name Sagittarius simply means archer. It doesn’t describe the fact that the archer isn’t just any old bloke with a bow and arrow, but is, indeed, a centaur, one of the two in the list of constellations. The other, Centaurus, is too far south to be seen from Michigan. And whose brightest star, Alpha Centauri, is in the closest star system to our solar system.
Centaurs, as a rule, were a rowdy bunch, the ancient Greek equivalent to a modern motorcycle gang. However, the centaur depicted by Sagittarius can be thought to be Chiron, though it can also be ascribed to Centaurus. Chiron was learned, a teacher and physician. I’ve noticed that in some artist’s depictions of Chiron, he is teaching Achilles how to use the bow and arrow. He also taught medicine to Asclepius, the great physician, who is seen in the heavens as the constellation Ophiuchus, above and right of Sagittarius.
What most of us see in the stars here is maybe a bow drawn to shoot at the heart of Scorpius, or a stout little teapot as in the children’s song. It even has the Milky Way seeming to rise from the spout like steam. The teapot rises in the southeast as if standing upright, and as the night wears on, it rises and move westward, slowly tilting to pour out its tea on the southwestern horizon.
The area of Sagittarius and the Milky Way is a fantastic part of the sky to explore with binoculars or a low power telescope on moonless nights. At the head of this post is a photograph of Sagittarius and the Milky Way taken from my home, with lines and labels. It’s somewhat spoiled by the sky glow from Chum’s Corner, a small commercial center 3.6 miles away, from the lower left. Most binoculars will show open or galactic star clusters as fuzzy spots like nebulae, which are fuzzy because they are clouds. The older globular star clusters require larger amateur telescopes to resolve.
I’ve only pointed out one in the image, that’s M22, whose designation, we have fun with at star parties at the Sleeping Bear Dunes National Lakeshore, since the road M22 runs through the park. Which came first? That’s easy, Charles Messier cataloged his 22nd object before Michigan was a state or even had roads. Well, maybe there were a few, around Detroit and Sault Ste. Marie, back when the major “roads” were the Great Lakes, and the rest Indian trails.
A telescope, even a small one, will resolve open clusters, showing individual stars. Telescopes will show the shapes of nebulae if they are bright enough.
One nebula with a distinctive shape is M17. The descriptive name I first knew it as was the Omega Nebula, and also the Horseshoe Nebula. To me, it never looked like either. It looked like a check mark, or a somewhat short necked swan. And it also goes by those names too. The planetarium program I use a lot, Stellarium, also calls it the Lobster nebula. I’m not much for seafood, but it doesn’t look like a lobster, or maybe I’m not hungry enough.
M16, is the Eagle Nebula. It has an associated star cluster. My eyes are drawn to the star cluster. The nebulosity is very faint, and I usually can’t see it. Part of the nebula was famously photographed by the Hubble Space Telescope and called the Pillars of Creation. In actuality, they are the Pillars of Destruction as they are being blown away by the stellar winds of the star cluster.
M8 is the Lagoon Nebula, it also has an associated star cluster. In telescopes, it is crossed by a narrow dust cloud suggestive of a lagoon. Nearby M20 is the Trifid nebula, which has a low surface brightness and can easily be missed. It is crossed by three narrow dust clouds dividing it into three, or on closer inspection, four wedges.
These just scratch the surface. So with or without optical aid wander through the celestial wonders and star clouds of Sagittarius. You have August and September to do it in the evening before they set for another year.

Based on an article I wrote for the August 2022 issue of the Stellar Sentinel, the Newsletter of the Grand Traverse Astronomical Society.

08/08/2022 – Ephemeris – The ages of the features on the Moon

This is Ephemeris for Monday, August 8th. Today the Sun will be up for 14 hours and 21 minutes, setting at 8:59, and it will rise tomorrow at 6:38. The Moon, halfway from first quarter to full, will set at 3:03 tomorrow morning.

Looking up at the gibbous Moon tonight, at the various patches of light and dark gray. Did you ever wonder how planetary scientists could piece together the history of our satellite? Other than studying photographs of the Moon, we have samples to study brought back be the Apollo astronauts, the Russians, and most recently the Chinese. We have the Lunar Reconnaissance Orbiter, which has photographed, and otherwise studied the surface and environment of the moon up close for 13 years so far. Something of the Moon’s history can be seen even with a small telescope. Craters showing rays, that has bright ejecta are newer than craters with faint ejecta, which are newer than craters with no ejecta marks. And so on.

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

Names and ages of selected lunar features via GIF animation for the Moon as it will appear tonight, August 8, 2022. Ages are in billions of years, with the oldest features being created 4.55 billion years ago. Source: Virtual Moon Atlas application. It can be downloaded from a link from the right panel of this page. GIF created using GIMP and LibreOffice Draw apps.

Here’s a link to the Planetary Society article Relative and absolute ages in the histories of Earth and the Moon: The Geologic Time Scale by Emily Lakdawalla: https://www.planetary.org/articles/09301225-geologic-time-scale-earth-moon

08/05/2022 – Ephemeris – Star Party tonight at the Joseph H. Rogers Observatory

This is Bob Moler with Ephemeris for Friday, August 5th. Today the Sun will be up for 14 hours and 29 minutes, setting at 9:03, and it will rise tomorrow at 6:34. The Moon, at first quarter today, will set at 12:45 tomorrow morning.

Tonight, the Grand Traverse Astronomical Society will host a star party at Northwestern Michigan College’s Rogers Observatory from 10 pm to midnight, if it’s clear. The first quarter Moon, and the planet Saturn, will be seen. Toward the end of the evening, Jupiter will make an appearance. Saturn is always magnificent with its rings, and Jupiter with its moons and cloud bands. Also, visible will be some brighter wonders beyond the solar system. Nebulae, which are clouds of gas, and great clusters of stars. Views from one of the observatory telescopes will be available via Zoom, link at gtastro.org. Some society members will also bring their telescopes for displaying the sky for attending visitors. The observatory is located south of Traverse City on Birmley Road. The approach to the observatory from Keystone Road from the south may be blocked by the construction of a roundabout at the Keystone-Cass Rd intersection.

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

Telescopes set up by members of the Grand Traverse Astronomical Society at the back of Northwestern Michigan College’s Joseph H. Rogers Observatory on August 3, 2018. Credit mine.

This may be the first time since 2019 that members will set their telescopes out behind the observatory for a star party. The telescope in the small dome is the one used for Zoom views of the Moon and possibly Saturn. Saturn will be blocked by trees for most of the evening, except from the observatory dome which is high enough, so Saturn will clear the trees sooner.

The sky is forecast to be partly cloudy, whatever that means. The Clear Sky Chart for the observatory shows that it will be clear. There is also a possibility of haze from the forest fires out west, dimming the sky and making observation of deep sky objects more difficult.

Events of the evening:

The first quarter Moon will already be up and will set at 12:45 am
9:03 pm – sunset
9:24 pm – Saturn rises*
10:20 pm – Nautical twilight ends
11:02 pm – Jupiter rises*
11:07 pm – Astronomical twilight ends

* It may be at least a half hour after rising before the image of these planets become half way sharp, due to the great amount of atmosphere we are looking through to see them. The higher in the sky they are, the better they will appear.

08/04/2022 – Ephemeris – The Late Heavy Bombardment

This is Bob Moler with Ephemeris for Thursday, August 4th. Today the Sun will be up for 14 hours and 32 minutes, setting at 9:04, and it will rise tomorrow at 6:33. The Moon, 1 day before first quarter, will set at 12:19 tomorrow morning.

The face of the Moon is nearly half uncovered from our point of view, with first quarter occurring at 7:06 tomorrow morning. It shows the string of lunar seas, those gray areas on the moon which lead to the terminator, the Moon’s sunrise line. There are even more and larger seas on the east half of the Moon, as we see it. Most were created about 3.9 billion years ago by asteroid strikes. The same thing happened to the Earth, but plate tectonics destroyed the evidence. Not so on the Moon. The result, many planetary scientists think, was the Late Heavy Bombardment, caused by the changing orbits of mainly Saturn, Uranus and Neptune disrupting the smaller asteroids, and sending them careening through the solar system.

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

First quarter Moon with prominent seas labeled. Created using Stellarium, GIMP and LibreOffice.

Nice model infographic: Evolution of the solar system. Step 6, with the exchange of Neptune’s and Uranus’ orbits, cause the Late Heavy Bombardment. The Nice model isn’t that nice. It’s named for Nice, France, the city where the model was first developed. The original on the web page was smaller. I enlarged it and sharpened it a bit, so it’s more readable. Credit: Nora Eisner.

The above infographic is from the blog post at https://blog.planethunters.org/2019/04/29/formation-of-our-solar-system/ by Nora Eisner.

08/03/2022 – Ephemeris – Let’s search for the naked-eye planets for this week

This is Ephemeris for Wednesday, August 3rd. Today the Sun will be up for 14 hours and 34 minutes, setting at 9:05, and it will rise tomorrow at 6:32. The Moon, 2 days before first quarter, will set at 11:56 this evening.

Let’s search for the naked-eye planets for this week. All but one of the naked-eye planets are in the morning sky, That one is Mercury, too close to the Sun to be seen in the evening. At 5:30 tomorrow morning, the planets will be spread out from brilliant Venus low in the east-northeast to Saturn in the southwest. Mars will be a lot higher than Venus in the southeast. Jupiter is farther to the right in the south. Mars is dimmer than Jupiter, but is slowly getting brighter as the Earth creeps up on it. Saturn ends the line of planets much lower than Jupiter in the southwest. Tonight, Saturn will rise about 9:33 pm in the east-southeast, though it won’t be an official evening planet until it rises before sunset, which is 11 days away.

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 annotated Moon for 10:30 this evening, August 3, 2022. Labels are centered on the feature they name. The crater Theophilus isn’t as prominent as it would have been 12 hours earlier, when it was nearer the terminator, the sunrise line. Search for it in the box above, right on this page, where I have more to say about it. It’s one of my favorite craters. Created using Stellarium, Libreoffice Draw, and GIMP.

Morning planets at 5:30 am tomorrow, August 4, 2022. With summer almost half over, the bright winter stars begin to appear in morning twilight along with the planets. Click on the image to enlarge it. The span of the planets from Venus to Saturn is 148 degrees. Click on the image to enlarge it. Created using Stellarium.

Views of Saturn, Jupiter, and Venus (north up) as they would be seen in a small telescope, with the same magnification, tomorrow morning at 5:30 am, August 4, 2022. I do not show planets less than 10 seconds of arc in diameter. Apparent diameters: Saturn 18.73″, its rings 43.63″; Jupiter 45.54″. Mars is not shown, its apparent diameter is 8.41″, 84.7% illuminated; Venus 10.64″, 93.2% illuminated. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on August 3, 2022. The night ends on the left with sunrise on the 4th. Notice that all the naked-eye planets except Mercury are in the morning sky now. That’s about to change in a week and a half, when Saturn moves into the evening sky when it reaches opposition from the Sun on the 14th. Click on the image to enlarge it. Created using my LookingUp program.