07/16/2021 – Ephemeris – The best time to see detail on the Moon (IMHO)

July 16, 2021 Comments off

This is Ephemeris for Friday, July 16th. Today the Sun will be up for 15 hours and 11 minutes, setting at 9:24, and it will rise tomorrow at 6:13. The Moon, 1 day before first quarter, will set at 1:08 tomorrow morning.

I consider the week centered on the first quarter moon to be the best time to view the Moon in a telescope. The best part of the Moon to view is near the terminator. The terminator is the sunrise line on the moon that we see before full moon, and the sunset line we see after full moon. The terminator is where the shadows are longest on the Moon and indeed on the Earth, with the low Sun in the sky. The Moon has lots of craters in its south or bottom part. We call that the lunar highlands, which is completely saturated with craters. Personally, I like craters. The darker lava plains that were initially called seas (the name stuck). They are flat and nearly featureless unless seen very close to the terminator, where the slight wrinkle ridges can be spotted.

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

The Moon tonight

The Moon tonight at 11 pm, July 16, 2021, about a day and 7 hours before the instant of first quarter. Note the shadows that bring out the craters near the terminator. Created using Stellarium.

Wrinkle ridges

Wrinkle ridges on the floor of a lunar sea (lava plain). These are only visible at a very low sun angle near the terminator. I can find no information on this image, but apparently it was taken in lunar orbit. This is much sharper detail than can be seen from earth.

 

07/15/2021 – Ephemeris – What the Chinese saw in the face of the Moon

July 15, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, July 15th. Today the Sun will be up for 15 hours and 13 minutes, setting at 9:25, and it will rise tomorrow at 6:12. The Moon, 2 days before first quarter, will set at 12:45 tomorrow morning.

Looking at the Moon tonight with the naked eye or binoculars, the dark patches called seas, which are really lava filled plains, make out the ears, head, and top part of the body of a rabbit that appears upside down. It’s the Chinese Jade Rabbit, Yutu. The seas involved, with their English names are: Serenity, the top of its body; Tranquility, its head; the more prominent ear is Fertility; while the other ear is a combination of the Bay of Roughness and Sea of Nectar. Yutu is the pet rabbit of the Moon goddess Chang’e, who flew to the Moon to escape her pursuers. The Chinese space agency has named all their moon landers Chang’e and their lunar rovers Yutu in their honor.

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

The Moon tonight with the Jade Rabbit

The Moon tonight with the Jade Rabbit delineated in the seas and one bay the dark lava covered plains of the Moon. Created using Stellarium.

The Jade Rabbit seen on a full moon

The Jade Rabbit seen on a full moon rotated close to what tonight’s Moon is. Actually, the ancient Chinese saw the rabbit pounding medicine.

07/14/2021 – Ephemeris – It’s Wednesday, do you know where your naked-eye planets are?

July 14, 2021 Comments off

This is Bob Moler with Ephemeris for Wednesday, July 14th. Today the Sun will be up for 15 hours and 15 minutes, setting at 9:26, and it will rise tomorrow at 6:11. The Moon, 3 days before first quarter, will set at 12:23 tomorrow morning.

Let’s search for the naked-eye planets for this week. Venus can be spotted low in the west-northwest twilight by 10 pm or a little after. It will set at 10:57 pm. Venus will be spending the rest of summer low in the western sky, and not be as conspicuous as it usually is as the Evening Star. Mars’ visibility is a real problem. It will be to the right and a bit below Venus in the evening, and will set at 10:52 pm. It’s much dimmer than Venus, so I doubt anyone at our northern latitude could spot it. Saturn and Jupiter, are seen starting very late in the evening and best in the morning sky. Saturn will rise at 10:18 pm. Brighter Jupiter will rise at 11:09 pm, both in the east-southeast. By 5 am, these two planets will be in the southern sky in the morning twilight.

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

Venus, Mars and the Moon in evening twilight

Venus, Mars and the Moon in evening twilight at 10:15 pm, about 50 minutes after sunset on July 14, 2021. Created using Stellarium.

Binocular Moon

The Moon as it might appear in binoculars or small telescope this evening, July 14, 2021. Created using Stellarium.

Saturn rising in the southeast

Saturn, rising in the southeast at 11 pm, about an hour and a half after sunset tonight, July 14, 2021. Astronomical twilight here has not yet ended. The Teapot asterism of Sagittarius is seen in the south-southeast. Scorpius’ tail, not shown, is scraping the horizon in the south. Saturn is in Capricornus, with two of its stars visible above it. Click on the image to enlarge it. Created using Stellarium.

Jupiter and Saturn in the morning

Jupiter and Saturn at 5 am tomorrow morning. Click on the image to enlarge it. Created using Stellarium.

Telescopic views of what the planets might appear like tonight

The planets as seen in a telescope (north up) with the same magnification for the night of July 14/15, 2021. Times of the display are: Venus, 10:30 pm; Saturn and Jupiter, 5 am. Apparent diameters: Venus, 11.77″; Saturn 18.50″, its rings 43.09″; Jupiter, 46.99″. Mars has an apparent diameter of only 3.75″ and is not represented. 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).

Planets and the Moon on a single night sunset 071421 to sunrise 071521

Planets and the Moon at sunset and sunrise of a single night, starting with sunset on the right on July 14, 2021. The night ends on the left with sunrise on the 15th. Click on the image to enlarge. Created using my LookingUp program.

07/13/2021 – Ephemeris – Virgin Galactic had a successful full crew flight to the edge of space

July 13, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, July 13th. Today the Sun will be up for 15 hours and 16 minutes, setting at 9:26, and it will rise tomorrow at 6:10. The Moon, halfway from new to first quarter, will set at 11:59 this evening.

This past Sunday was Virgin Galactic’s first test passenger flight to what the United States calls space, past 50 miles altitude, in their VSS Unity spaceship. The four passengers for this test flight were all basically Virgin Galactic employees, including its founder, Richard Branson. The international definition of where space begins is 100 kilometers or 62 miles altitude. At either altitude, a suborbital spacecraft at its peak altitude would be traveling so slowly that the atmospheric effects are negligible. However, if a spacecraft were to pass through that altitude on reentry at over 17 thousand miles an hour, that’s an entirely different story. On July 20th Jeff Bezos will ride his New Shepard rocket up past 62 miles.

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

VSS Unity launch

Virgin Galactic’s Spaceship VSS Unity ignites its hybrid rocket engine after being dropped from its carrier aircraft Eve on a prior test flight to the edge of space. Credit Sky News.

VSS Unity under power

VSS Unity under power with its hybrid rocket motor. The fuel is a solid rubbery compound, with a nitrous oxide as the oxidizer. Powered flight lasts only 60 seconds to reach 56 miles in altitude. This is from a prior flight. Click on the image to enlarge it. Credit: Virgin Galactic.

Floating in zero G in VSS Unity 22

Floating in zero G in VSS Unity 22. I can imagine the announcement: “The seat belt sign has been turned off. You may float about the cabin.” At least for 5 minutes. Click on the image to enlarge it. Credit: Virgin Galactic video.

07/12/2021 – Ephemeris – Two cultures look at the star pattern of Cygnus the swan

July 12, 2021 Comments off

This is Ephemeris for Monday, July 12th. Today the Sun will be up for 15 hours and 18 minutes, setting at 9:27, and it will rise tomorrow at 6:09. The Moon, 3 days past new, will set at 11:33 this evening.

Last week I looked at the constellation of Cygnus the swan and the informal constellation or asterism made from most of its stars, the Northern Cross. Cygnus is the official International Astronomical Union constellation name. However, the indigenous Anishinaabe people of our area, and the northern Great Lakes, had another bird in mind when seeing these stars, which are now fairly high in the east in the evening: Ajijaak, (pronounced a-ji-jock) a Sand Hill crane. While the swan is flying, neck outstretched to the south through the Milky Way, the crane is flying northward with its long legs trailing behind. The bright star Deneb is at its head. I see more cranes than swans around here in recent years and hear their creaking-door-like calls, and can see a pair foraging, from time to time, in a field south of where I live.

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

Swan and the Crane constellations

The IAU Cygnus the swan and the Anishinaabe Ajijaak the crane constellations demonstrated via an animated GIF image. Click on the image to enlarge it. Credit Stellarium (both star lore images are embedded in Stellarium). The Anishinaabe image is from Ojibwe Giizhig Anung Masinaaigan – Ojibwe Sky Star Map created by A. Lee, W. Wilson, and C. Gawboy.

07/09/2021 – Ephemeris – Finding the constellation of Aquila the eagle

July 9, 2021 Comments off

This is Ephemeris for Friday, July 9th. Today the Sun will be up for 15 hours and 22 minutes, setting at 9:29, and it will rise tomorrow at 6:07. The Moon is new today, and won’t be visible.

Aquila the eagle is a constellation that lies in the Milky Way. It’s in the southeastern sky as it gets dark. Its brightest star, Altair, is one of the stars of the Summer Triangle, a group of three bright stars dominating the eastern sky in the evening now. Altair, in the head of the eagle, is flanked by two slightly dimmer stars, the shoulders of the eagle. The eagle is flying northeastward through the Milky Way. Its wings are seen in the wing tip stars. A curved group of stars to the lower right of Altair is its tail. Within Aquila, the Milky Way shows many dark clouds as part of the Great Rift that splits it here. The other summer bird is Cygnus the swan above and left of Aquila, flying in the opposite direction. It was said this was the eagle that attended the god Jupiter.

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

Addendum

Aquila finder animation

Animated Cygnus finder chart. Lyra the harp, Cygnus the swan, Delphinus the dolphin and Sagitta the arrow are also in the image. Can you find them? Click on the image to enlarge it. Created using Stellarium and GIMP.

07/08/2021 – Ephemeris – How to find the constellation of Cygnus the swan

July 8, 2021 Comments off

This is Ephemeris for Thursday, July 8th. Today the Sun will be up for 15 hours and 23 minutes, setting at 9:29, and it will rise tomorrow at 6:06. The Moon, 1 day before new, will rise at 5:23 tomorrow morning.

Halfway up the sky in the east at 11 pm is the constellation of Cygnus the swan, flying south through the Milky Way. It is also called the Northern Cross. At the left, the tail of the swan or the head of the cross is the bright star Deneb, one of the stars of the Summer Triangle. The next star to the right is Sadr the intersection of the body and the wings of the swan seen in flight, or the intersection of the two pieces of the cross. There are two or three stars farther to the right that delineate the swan’s long neck or upright of the cross, that ends with the star Alberio, a beautiful double star in telescopes, in the beak of the swan or foot of the cross. The crosspiece of the cross extends to the stars on either side of the intersection star Sadr, while the swan’s wings extend for a couple more stars each side.

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

Addendum

Cygnus finder animation

Animated Cygnus finder chart. Included also are, beside Deneb, the other stars of the Summer Triangle: Vega and Altair and their constellations Lyra the harp and Aquila. See if you can find them. Click on the image to enlarge it. Created using Stellarium.

07/07/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

July 7, 2021 Comments off

This is Ephemeris for Wednesday, July 7th. Today the Sun will be up for 15 hours and 24 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 2 days before new, will rise at 4:36 tomorrow morning.

Let’s search for the naked-eye planets for this week. Venus can be spotted low in the west-northwest twilight by 10 pm or a little after. It will set at 11:03 pm. Venus will be spending the rest of summer low in the western sky, and not be as conspicuous as it usually is as the Evening Star. Mars’ visibility is getting to be a real problem. It can be found to the left and a bit above Venus at 10:30 pm, and will set at 11:06 pm. Saturn and Jupiter, are seen best in the morning sky. Saturn will rise before midnight at 10:47 pm. It’s seen with the stars of Capricornus. Brighter Jupiter, to the left of Saturn, will rise at 11:34 pm. By 5 am, these two planets will be in the southern sky in the morning twilight.

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

Venus and Mars in the evening twilight

Venus and Mars in the evening twilight at 10:30 pm tonight, July 7, 2021. I’m not promising that Mars will be visible, since it’s now down to second magnitude. Created using Stellarium.

Saturn Finder animation for 11:30 pm

Saturn finder animation for 11:30 pm tonight, July 7, 2021. Click on the image to enlarge it. Created using Stellarium and GIMP.

Jupiter and Saturn at 5 am

Jupiter and Saturn at 5 am tomorrow morning, July 8, 2021. Created using Stellarium.

Mercury and the Moon at 5:15 am

Mercury and the Moon at 5:15 am tomorrow morning, July 8, 2021. Created using Stellarium.

Telescopic planets

The planets as seen in a telescope (north up) with the same magnification for the night of July 7/8, 2021. Times of the display are: Venus, 10:30 pm; Saturn and Jupiter, 5 am. Apparent diameters: Venus, 11.46″; Saturn 18.41″, its rings 42.88″; Jupiter, 46.18″. Mars has an apparent diameter of only 3.80″, and Mercury of 7.32 and are not represented. 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).

Planets and the Moon on a single night sunset 070721 to sunrise 070821

Planets and the Moon at sunset and sunrise of a single night, starting with sunset on the right on July 7, 2021. The night ends on the left with sunrise on the 8th. Click on the image to enlarge. Created using my LookingUp program.

07/06/2021 – Ephemeris – Looking at the constellation of Lyra the harp

July 6, 2021 Comments off

This is Ephemeris for Tuesday, July 6th. Today the Sun will be up for 15 hours and 26 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 3 days before new, will rise at 3:56 tomorrow morning.

High in the east at 11 p.m. can be found a bright star just above a small, narrow, but very distinctive parallelogram of stars. They are the stars of the constellation Lyra the harp. The bright star is Vega, the 5th brightest night-time star. To the Romans, the star Vega represented a falling eagle or vulture. Apparently they never made the distinction between the two species. It is a pure white star and serves as a calibration star for color and brightness. In the evening, it is the top-most star of the Summer Triangle. The harp, according to Greek mythology, was invented by the god Hermes. The form of the harp, in the sky, is as he had invented it: by stretching strings across a tortoise shell. Hermes gave it to his half-brother Apollo, who in turn gave it to the legendary musician Orpheus.

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

Addendum

Annimated Lyra finder chart

Animated Lyra finder chart. The lyre image not supplied by Stellarium but is from The World’s Earliest Music by Hermann Smith, Figure 60, A Project Gutenberg E-Book, and captioned “The Chelys or Greek Tortoiseshell Lyre”. Click on the image to enlarge it. Created using Stellarium and GIMP.

07/05/2021 – Ephemeris – Happy Aphelion Day

July 5, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, July 5th. Today the Sun will be up for 15 hours and 27 minutes, setting at 9:30, and it will rise tomorrow at 6:04. The Moon, halfway from last quarter to new, will rise at 3:24 tomorrow morning.

Today, the Moon and Sun are at their farthest from the Earth. For the Moon it’s called apogee, for the Sun it’s called aphelion. At 10:48 this morning the Moon will be at that point 251,842 miles (405,300 kilometers) away. The Sun will be farthest at 10:59 pm at a distance of 94 million, 452 thousand miles (152 million, 6 thousand kilometers) away. Because of the gravitational pull of the Moon and planets on the Earth, and the Pull of the planets, especially Jupiter on the Sun, the aphelion and perihelion or closest date in January don’t occur on the same date or same distance every year. The date wanders by a day or two each year. The entire distance variation for the Earth is plus or minus 1.5 million miles (2.4 million kilometers) over the year, but makes summer the longest season by a few days because the Earth moves slower when farther from the Sun, than when it is nearer.

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

Addendum

Earth's orbit

The Earth’s orbital ellipse, somewhat exaggerated, showing perihelion, aphelion and the seasons. Credit “Starts with a Bang” blog by Ethan Siegel.

Currently, summer is the longest season at 93.65 days, while winter is the shortest season at 88.99 days. (Source: Astronomical Tables of the Sun, Moon and Planets, Third Edition by Jean Meeus)