09/26/2022 – Ephemeris – The DART spacecraft will attempt to deflect an asteroid tonight, Artemis I launch postponed

September 26, 2022 Comments off

This is Ephemeris for Monday, September 26th. Today the Sun will be up for 11 hours and 57 minutes, setting at 7:32, and it will rise tomorrow at 7:35. The Moon, 1 day past new, will set at 8:07 this evening.

Tonight at 7:14 pm EDT (23:14 UTC), NASA’s DART spacecraft will collide with the tiny asteroid Dimorphos, which is orbiting the somewhat larger asteroid Didymos. They are potentially hazardous asteroids. The idea is to see what effect the collision has on the orbit of Dimorphos as it orbits Didymos at four tenths of a mile an hour. Trailing DART is an Italian CubeSat LiciaCube (pronounced LEE-cha-cube), which was launched from DART more 15 days ago to witness the collision. DART is an acronym for Double Asteroid Redirection Test, part of the Planetary Defense Program. Earth based radio and optical telescopes will assess if and how much the collision alters the orbit of Dimorphos. LICIAcube will return images of the collision, crater and the other side of Dimorphos. NASA will air it live on their channels.

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

Unlike the Artemis I launch, this event cannot be postponed. It will either hit Dimorphos at 7:14 pm or miss forever.

NASA DART

Graphic on NASA’s DART mission to crash a small spacecraft into a mini-asteroid to change its trajectory as a test for any potentially dangerous asteroids in the future. Click on the image to enlarge it. Credit: AFP / AFP (Agence France-Presse)

A Note from EarthSky.org:

If you want to watch the event live, coverage begins at 6 p.m. EDT (22 UTC) on September 26, 2022, on NASA’s website. You can also watch it via Facebook, Twitter and YouTube.

Artemis I news

The Artemis I launch, scheduled for Tuesday, September 27, has been postponed due to the threat from tropical storm Ian.

09/23/2022 – Ephemeris – Weather prospects look dim for a star party tomorrow night, but we won’t know for sure until we get closer

September 23, 2022 Comments off

Update: The Star Party has been Canceled

Here’s a deep dark secret:  Ephemeris programs are recorded the Sunday night for the week beginning Tuesday through the following Monday. However, the posting of the scripts here is generally done the night before the air date. From this vantage point, with the weather forecast not changing for the past week, it looks like we’ll be greeted with not only clouds but rain. The operative words in the post below are “weather permitting”, Which explains the headline.

This is Ephemeris for Friday, September 23rd. Today the Sun will be up for 12 hours and 7 minutes, setting at 7:38, and it will rise tomorrow at 7:32. The Moon, 2 days before new, will rise at 5:54 tomorrow morning.

Weather permitting, a star party will be held tomorrow night, Saturday, September 24th at Sleeping Bear Dunes National Lakeshore at the Dune Climb starting at 8 pm. The star party will be hosted by the Park Rangers and members of the Grand Traverse Astronomical Society (GTAS), who will bring their telescopes to view the heavens, including the planets Jupiter and Saturn plus the wonders of the summer Milky Way. The telescopes will be set up in the parking area closest to the dune. Saturn will be available immediately, while we wait for Jupiter to rise higher. As it gets darker, more and more wonders of the Milky Way will be seen. They include star clusters and nebulae, clouds of gas and dust from which stars form, and which are expelled in the process of star death.

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

If you are not sure if it will be clear enough to hold the star party, please call the park rangers at 231-326-4700, ext. 5005, for a voicemail message with the decision. Alternately, gtastro.org, the GTAS website, will also display the status of the star party, and if it is canceled by 5 pm on Saturday the 24th.

Dune Climb Setup

This in the beginning of setup for the October 21, 2017 star party at the dune climb. Taken early, looking to the south-southwest, while there was enough light. The dune blocks up to 12 degrees from the southwest to northwest, but the rest of the horizon is quite low. Note the lone trees on the hill right of the top of the ladder. They are my targets to align my telescope’s finder. Once, while performing the alignment, a fog bank tumbled over that ridge and wiped it out for a time. It was eventually a good night.

We’ve had more than our share of iffy weather at or travelling to the site. A good share of GTAS members live in the Traverse City area, some 30 miles east of the park. More than a few of us, over the years, have driven through rain showers, on our way to the park, for a successful star party. Here’s a link to another night with iffy weather, this time with a lunar eclipse.

09/22/2022 – Ephemeris – Autumn will begin this evening

September 22, 2022 Comments off

This is Ephemeris for Thursday, September 22nd. Today the Sun will be up for 12 hours and 10 minutes, setting at 7:40, and it will rise tomorrow at 7:31. The Moon, 3 days before new, will rise at 4:46 tomorrow morning.

The season of fall is about to, ah well, fall upon us and in a few weeks so will the leaves. At 9:04 this evening (1:04 UT tomorrow) the Sun will cross the celestial equator heading south. The celestial equator is an imaginary line in the sky above the earth’s equator. At that point, the Sun will theoretically set at the North Pole and rise at the South Pole. The day is called the autumnal equinox and the daylight hours today is 12 hours and 10 minutes instead of 12 hours exactly. That’s due to our atmosphere and our definition of sunrise and sunset. The reason for the cooler weather now and the cold weather this winter is that the length of daylight is shortening, and the Sun rides lower in the sky, spreading its heat over a larger area, thus diluting its intensity.

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

Sun's path on the equinox for TC-Interlochen

The Sun’s path through the sky on an equinox day from the Traverse City/Interlochen area in Michigan. The Sun is plotted every 15 minutes. This is a stereographic projection which compresses the image near the zenith and enlarges the image towards the horizon. Note that the Sun rises due east and sets due west. Created using my LookingUp program.

Sunrise on the autumnal equinox

That is not a pumpkin on the head of the motorcyclist. That’s the Sun rising as I’m traveling east on South Airport Road south of Traverse City, MI on the autumnal equinox. This is the east-west section of the road. The Sun is rising over the hills some 6 miles to the east. When the Sun is on the celestial equator, it rises due east and sets due west. Credit: Bob Moler.

Autumnal equinox from space

Image from the Earth Polychromatic Imaging Camera (EPIC) on NOAA’s DSCOVR satellite in halo orbit around the Earth-Sun L-1 point 1 million miles sunward from the Earth on the autumnal equinox of 2016. North America is in the upper right of the globe.

Earth's position at the solstices and equinoxes

Earth’s position at the solstices and equinoxes. This is an not to scale oblique look at the Earth’s orbit, which is nearly circular. The Earth is actually farthest from the Sun on July 4th. Click on the image to enlarge. Credit: ESO (European Southern Observatory), which explains the captions in German and English.

09/21/2022 – Ephemeris – Let’s search for the naked-eye planets for this week

September 21, 2022 Comments off

This is Ephemeris for Wednesday, September 21st. Today the Sun will be up for 12 hours and 13 minutes, setting at 7:41, and it will rise tomorrow at 7:29. The Moon, halfway from last quarter to new, will rise at 3:38 tomorrow morning.

Let’s search for the naked-eye planets for this week. Only one of the naked-eye planets is in the evening sky. Mercury is south of the Sun and cannot be seen. It will pass between the Earth and Sun on Friday and enter the morning sky. As it gets darker, Saturn can be seen in the southeast. Jupiter, though not officially an evening planet, will rise in the east in twilight at 7:54 pm. It is seen against the stars of Pisces now, moving slowly retrograde or westward. At 6:30 am tomorrow, two of the three remaining morning planets will be Mars high in the south, above the winter constellation of Orion, and Jupiter very low in the west. The thin waning crescent Moon will be in the east then. Venus will rise at 6:47 into bright twilight.

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

Jupiter and Saturn at 9 pm

Jupiter and Saturn at 9 pm tonight, September 21, 2022. Created using Stellarium.

Morning planets and waning crescent Moon

Animation of the morning planets and the waning crescent Moon at 6:30 am tomorrow, September 22, 2022. Star labels are shown alternately, since they clutter the image. Click on the image to enlarge it. Created using Stellarium and GIMP.

The waning crescent Moon as it might be seen in binoculars or a small telescope. The dark area on the left side of the Moon is Oceanus Procellarum (Ocean of Storms). The dark spot near the bottom of the Moon is the crater Grimaldi. Created using Stellarium.

Telescopic views of Saturn Jupiter and Mars

Telescopic views of Saturn Jupiter and Mars (north up) as they would be seen in a small telescope, with the same magnification. The times vary for each planet. Jupiter is shown twice, at 9 pm and 6:30 am, since its moons, especially Io and Europa, move rapidly. I do not show planets less than 10 seconds of arc in diameter. Apparent diameters: Saturn 18.33″, its rings 42.69″; Jupiter 49.85″. Mars 11.21″, 86.6% illuminated. Mars’ distance is 78 million miles (125 million kilometers). The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).

In the above chart, it may appear that Jupiter’s Great Red Spot didn’t move very much. However, the 9.5 hours between the images is a bit less than one Jovian day, so the spot actually made almost one complete rotation. In this view, features on the face of Jupiter rotate from left to right. Satellites behave similarly. They move left to right if in front of the planet, and right to left if behind.

Planets and the Moon on a single night

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on September 21, 2022. The night ends on the left with sunrise on the 22nd. Click on the image to enlarge it. Created using my LookingUp program and GIMP.

09/20/2022 – Ephemeris – Finding the constellation of Pegasus the flying horse

September 20, 2022 Comments off

This is Ephemeris for Tuesday, September 20th. Today the Sun will be up for 12 hours and 16 minutes, setting at 7:43, and it will rise tomorrow at 7:28. The Moon, 3 days past last quarter, will rise at 2:33 tomorrow morning.

Rising about a third of the way up the sky in the east as it gets dark around 9 pm can be found one of the great autumn constellations: Pegasus the flying horse of Greek myth. Its most visible feature is a large square of four stars, now standing on one corner. This feature, called the Great Square of Pegasus, represents the front part of the horse’s body. The horse is quite aerobatic, because it is seen flying upside down. Remembering that fact, the neck and head is a bent line of stars emanating from the right corner star of the square. Its front legs can be seen in a gallop extending to the upper right from the top star of the square. From the left star extend, not hind legs but the constellation of Andromeda, the princess rescued with the help of Pegasus.

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

Pegasus-Andromeda finder

Pegasus & Andromeda animated finder chart for 9 pm in mid-September. To the upper left are most of the stars of the “W” shape of Cassiopeia the queen, Andromeda’s mother. Created using Stellarium and GIMP.

Pegasus, Andromeda and Cassiopeia plus other constellations are characters in the great star story of autumn which I relate here.

09/19/2022 – Ephemeris – Finding the constellation Cepheus

September 19, 2022 Comments off

This is Ephemeris for Monday, September 19th. Today the Sun will be up for 12 hours and 19 minutes, setting at 7:45, and it will rise tomorrow at 7:27. The Moon, 2 days past last quarter, will rise at 1:30 tomorrow morning.

There’s a faint constellation in the northeast above the W shaped constellation of Cassiopeia. It’s a nearly upside down church steeple of a constellation called Cepheus the king, and husband of queen Cassiopeia. Cepheus’ claim to modern astronomical fame is that one of its stars, Delta (δ) Cephei, is the archetype for the important Cepheid variable stars. Delta is the bottom most of a trio of stars at the right corner of the constellation. In the early 20th century, Henrietta Leavitt discovered that Cepheids in the nearby galaxy the Large Magellanic Cloud varied in brightness with a period that was related to their average brightness. This meant that Cepheids could be used as standard candles to measure the great distances to other galaxies.

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

Cassiopeia and Cepheus finder animation

Cassiopeia and Cepheus finder animation looking in the northeast at 9 pm or about an hour after sunset in mid-September. Also labeled is Delta (δ) Cephei. Created using Stellarium and GIMP.

Delta_Cephei_lightcurve

Light Curve of Delta Cephei. The pulsation period is 5.367 days. Note the Magnitude vertical axis, the lower the magnitude the brighter the star is. Blame that on the Greek astronomer Hipparchus, 2nd century BC. It’s like golf scores; the lower the score, the better the golfer, and for magnitudes, the brighter the star. Credit: Thomas K Vbg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=13887639.

09/16/2022 – Ephemeris – Alberio: a double star that showcases star colors

September 16, 2022 Comments off

This is Ephemeris for Friday, September 16th. Today the Sun will be up for 12 hours and 28 minutes, setting at 7:51, and it will rise tomorrow at 7:24. The Moon, 1 day before last quarter, will rise at 11:03 this evening.

Alberio is the name given to the star that is in the head of the constellation of Cygnus the swan, which is high in the east these evenings. It is also at the foot of the asterism or informal constellation of the Northern Cross. To the naked eye Albireo looks like a single star, however even in small telescopes its true nature is revealed. It’s a double star whose individual star colors are strikingly different Its brightest star is yellow, and the dimmer star is blue. While star colors are subtle, these two, due to their apparent closeness, make an obvious color contrast. Unlike what your interior decorator says: In stars, blue is hot, yellow, orange and red are cool. The two stars are too far apart to be considered a binary star system, but appear to move together in space. It is what is called an optical double, though they’re both around 430 light years 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

Albireo finder animation

Animated Albireo finder chart. Albireo is located in the head of Cygnus the swan, or at the base of the Northern Cross. Tagged stars are, beside Albireo, the stars of the Summer Triangle: Deneb, Vega and Altair plus the star at the junction of the upright and crosspiece of the cross, Sadr. Created using Stellarium.

Albireo photographed in a telescope

Albireo, captured at high magnification by the staff of the Smithsonian Institution. Informally, at star parties, I call it the U of M Star because it displays the University of Michigan’s Maize and Blue colors.

A note about star colors

The color of a star is dependent on its surface temperature. The term surface is a misnomer, because stars do not have a surface, at least not a solid one, being gaseous in nature. The only exception I can think is a neutron star, which is packed with neutrons. We consider the Sun’s photosphere synonymous with “surface”. The photosphere of the Sun is where the energy transport from the core changes from convection to radiation. The color of the Sun is a measure of the temperature of the photosphere. The color sequence from the coolest to the hottest is: red, orange, yellow, white and blue. The light emitted by a star is not a pure color, but a distribution of colors, whose peak shifts along that range. There is much more to tell, but that’s beyond the scope of this post.

09/15/2022 – Ephemeris – Finding Cassiopeia this time of year

September 15, 2022 Comments off

This is Ephemeris for Thursday, September 15th. Today the Sun will be up for 12 hours and 31 minutes, setting at 7:53, and it will rise tomorrow at 7:22. The Moon, 2 days before last quarter, will rise at 10:30 this evening.

In the northeastern sky is a letter W shaped constellation of Cassiopeia, the queen of Greek myth. I can’t say Cassiopeia is rising in the northeast, because it never sets for us in northern Michigan. This time of year it skirts above the northern horizon during the daytime. One of Cassiopeia’s claims to historical astronomical fame is that it’s the location of Tycho’s Star, a supernova discovered in 1572 by Danish astronomer Tycho Brahe, the last of the great astronomers prior to the invention of the telescope. Tycho was able to prove that the temporary phenomenon was actually a star in the heavens, disproving the Greek notion that the heavens were changeless and perfect. The Chinese had already known that, calling them Guest Stars.

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

Cassiopeia finder animation

Cassiopeia finder animation for 10 pm tonight, September 15th. One cannot miss the distinctive W. Created using Stellarium.

Tycho's Supernova 1574A

Tycho’s Supernova 1574A, as simulated in Stellarium for mid-November 1572.

Tycho's Supernova remnant seen in x-rays

Tycho’s Supernova remnant, seen in x-rays by the orbiting Chandra X-ray Observatory. Credit: NASA / Chandra

09/14/2022 – Ephemeris – Let’s search for the naked-eye planets for this week

September 14, 2022 Comments off

This is Ephemeris for Wednesday, September 14th. Today the Sun will be up for 12 hours and 34 minutes, setting at 7:55, and it will rise tomorrow at 7:21. The Moon, 3 days before last quarter, will rise at 10:02 this evening.

Let’s search for the naked-eye planets for this week. Two of the naked-eye planets are in the evening sky. Mercury sets too close to the Sun to be seen in the evening. But as it gets darker, Saturn can be seen in the southeast. Jupiter, still officially a morning planet, rises in the east around 8:23 pm. It is seen against the stars of Pisces now, moving slowly retrograde or westward. At 6:30 am tomorrow the three morning planets will be spread out from brilliant Venus on the horizon in the east-northeast, if you can see it at all, to Mars high in the south-southeast below the Moon and next to the bright reddish star Aldebaran to Jupiter in the west-southwest. Mars is among the stars seen rising on late autumn and early winter evenings.

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

Jupiter and Saturn at 9 pm

Jupiter and Saturn at 9 pm tonight, September 14, 2022. Created using Stellarium.

The waning gibbous moon as seen in binoculars or low power telescope at 10:30 tonight, September 14, 2022. Labels are centered on their feature. Created using Stellarium, labels using LibreOffice Draw, and GIMP for animation.

Morning planets and Moon with the Moon and the bright winter stars

The morning planets with the Moon and the bright winter stars at 6:30 am tomorrow, September 15, 2022. Click on the image to enlarge it. Click on the image to enlarge it. Created using Stellarium.

Telescopic views of Saturn Jupiter and Mars

Telescopic views of Saturn Jupiter and Mars (north up) as they would be seen in a small telescope, with the same magnification. The times vary for each planet. Saturn is shown at 9 pm. Jupiter is shown twice, at 9 pm and 6:30 am, since its moons, especially Io and Europa, move rapidly. Mars is shown at 6:30 am. I do not show planets less than 10 seconds of arc in diameter, so Venus isn’t shown. Apparent diameters: Saturn 18.47″, its rings 43.02″; Jupiter 49.66″. Mars 10.70″, 86.0% illuminated; Venus (not shown) 9.89″, 98.5% 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) and GIMP.

Planets and the Moon on a single night

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on September 14, 2022. The night ends on the left with sunrise on the 15th. Click on the image to enlarge it. Created using my LookingUp program, and GIMP.

09/13/2022 – Ephemeris – SpaceX Crew-5 flight to the ISS will be commanded by first Native American female astronaut

September 13, 2022 Comments off

This is Ephemeris for Tuesday, September 13th. Today the Sun will be up for 12 hours and 37 minutes, setting at 7:57, and it will rise tomorrow at 7:20. The Moon, 3 days past full, will rise at 9:38 this evening.

On or around October 3rd a SpaceX Crew Dragon capsule will be launched to the International Space Station with an international crew of four with the first female Native American astronaut Nicole Mann as commander, pilot Josh Cassada, both NASA astronauts, Japanese astronaut Koichi Wakata, and Russian cosmonaut Anna Kikina. Nicole Mann, a member of the Round Valley Indian Tribes of northern California, is also the first female commander of a Commercial Crew spacecraft. She was originally assigned to the Boeing CST-100 Starliner, but was transferred to the SpaceX Dragon due to the prolonged problems with the former vehicle. Crew 5 will be a part of Expeditions 67 and 68 on the International Space Station.

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

SpaceX Crew 5 Official Portrait

SpaceX Crew-5 Official Crew Portrait – Left to right: Anna Kikina, Josh Cassada, Nicole Mann and Koichi Wakata.