Archive
09/25/2020 – Ephemeris – The Sleeping Bear Dunes National Lakeshore Virtual Star Party is tonight
This is Ephemeris for Friday, September 25th. Today the Sun will be up for 11 hours and 59 minutes, setting at 7:33, and it will rise tomorrow at 7:35. The Moon, 2 days past first quarter, will set at 1:51 tomorrow morning.
Tonight the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society may hold the park’s 50th anniversary online star party this evening starting around 8 pm via the Zoom app available for Android smart phones, iPhones and computers. Instructions for joining are on the society’s web site gtastro.org and the Sleeping Bear Dunes Facebook page. Images will be captured live, if it’s clear, from Northwestern Michigan College’s Joseph H Rogers Observatory. The images will be pretty much what is seen at the telescope eyepiece, and definitely not Hubble Space Telescope quality, which take days to process. Visible will be the Moon, Jupiter, Saturn and later on Mars plus some really neat objects beyond the solar system. it all begins at 9 pm.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Preview of Saturn imaged by Professor Jerry Dobek at Northwestern Michigan College’s Joseph H. Rogers Observatory.
Preview of Mars imaged by Professor Jerry Dobek at Northwestern Michigan College’s Joseph H. Rogers Observatory. Notice at top the small whitish patch, it a polar cap at the south pole of Mars. There are also some darker patches on the upper half of the image.
09/24/2020 – Ephemeris – Phosphine found in Venus’ atmosphere
This is Ephemeris for Thursday, September 24th. Today the Sun will be up for 12 hours and 2 minutes, setting at 7:35, and it will rise tomorrow at 7:34. The Moon, 1 day past first quarter, will set at 12:49 tomorrow morning.
Three years ago astronomers began to discover phosphine in the atmosphere of Venus. The chemical phosphine is related to ammonia in that it has three hydrogen atoms. They are tied to phosphorus rather than to nitrogen as is ammonia. It can also be created biologically, as it is almost entirely created on the Earth. It also is produced by volcanoes, and Venus has evidence of volcanic action. After three years of observation and looking for and ruling out non biological origins of phosphine they made public the announcement last week Monday. The detection was made in the millimeter wavelengths of the electromagnetic spectrum between microwave and the infrared. Is life responsible? A space probe or many to Venus will be needed to find out to help solve the mystery.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Clouds on the night side of Venus as seen in the infrared from the Japanese spacecraft Akatsuki, the only active spacecraft currently orbiting Venus. Credit JAXA / ISAS / DARTS / Damia Bouic
Some links for more information:
Original article – https://www.nature.com/articles/s41550-020-1174-4,
From Phil Plait’s Bad Astronomy: https://www.syfy.com/syfywire/so-astronomers-may-have-found-evidence-of-life-on-venus
09/23/2020 – Ephemeris – Let’s look at a the naked-eye planets for this week
This is Ephemeris for Wednesday, September 23rd. Today the Sun will be up for 12 hours and 5 minutes, setting at 7:37, and it will rise tomorrow at 7:32. The Moon, at first quarter today, will set at 11:53 this evening.
Let’s look at a the naked-eye planets for this week. Jupiter and Saturn are both low in the southern sky at 9 pm. Jupiter is the very bright one. To the left of it will be the somewhat dimmer Saturn. They are now seemly to close a tiny bit since Jupiter is resuming its eastward motion, and they will cross paths in December. Jupiter will set first at 1:11 tomorrow morning with Saturn following at 1:51. The next planet visible will be Mars which will rise at 8:44 pm. Its now down to 39.8 million miles (64.0 million km) away, as the Earth very slowly overtook it by 1.5 million miles (2.6 million km) last week as the Earth is moving nearly abreast of it. Brilliant Venus will rise at 3:53 am as it retreats toward the Sun.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The planets visible at 9 pm or about an hour and a half after sunset tonight September 23, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.
The first quarter Moon tonight as it might appear in binoculars or a low power telescope. Created using Stellarium.
Mars, and Venus and the morning stars at 6 am or an hour and a half before sunrise tomorrow morning September 24, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.
The planets as seen in a telescope (north up) with the same magnification for the night of September 23/24, 2020. Times of the display are: Jupiter and Saturn, 9 pm; Mars, Midnight; Venus, 6 am. Apparent diameters: Jupiter, 41.42″; Saturn, 17.40″, rings, 40.52″. Mars, 21.96″, and Venus 16.25″. Mars also displays an enlargement showing surface detail. Mars will be closest to the Earth this go-a-round on October 6. The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on September 23, 2020. The night ends on the left with sunrise on the 24th. Click on the image to enlarge. Created using my LookingUp program.
09/22/2020 – Ephemeris – Autumn starts this morning
This is Bob Moler with Ephemeris for Tuesday, September 22nd. Today the Sun will be up for 12 hours and 8 minutes, setting at 7:39, and it will rise tomorrow at 7:31. The Moon, 1 day before first quarter, will set at 11:05 this evening.
Fall is about to a, well… fall upon us and in a few weeks so will the leaves. At 9:31 this morning (13:31 UTC*) 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 8 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 event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
* UTC – Coordinated Universal Time. Greenwich Mean Time if you haven’t kept up. Zulu if you’re in the military.
The Sun crossing the celestial equator in three steps: 9:31 am Sept 21, 22, and 23 2020. Created using Stellarium and GIMP.
The Sun’s path through the sky on the equinox day from Traverse City, MI. Created using my LookingUp program.
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. Credit: Bob Moler.
09/21/2020 – Ephemeris – This is the last full day of summer
This is Ephemeris for Monday, September 21st. Today the Sun will be up for 12 hours and 11 minutes, setting at 7:41, and it will rise tomorrow at 7:30. The Moon, 2 days before first quarter, will set at 10:24 this evening.
Enjoy the last full day of summer. Summer will last until 9:31 am (05:31 UTC) tomorrow when the center of the Sun will cross the celestial equator, an imaginary line above the Earth’s equator, heading southward. At that instant autumn will begin for Earth’s northern hemisphere and spring will begin in the southern hemisphere. Shortly, for us, the Sun will be up less than half the day. The day and the point in the sky that the Sun crosses is called the autumnal or September equinox. The word equinox means equal night, implying the equality of day and night. Geometrically that’s true, but the Earth’s atmosphere and the definition of sunrise and sunset, prolong daylight by a few more minutes. The amount of heat we are getting and will get from the Sun cannot sustain our current temperatures, and it will get a lot colder on average before it gets warmer again.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Sun crossing the celestial equator in the sky moving southward in three steps: 9:31 am Sept 21, 22, and 23 2020. The vertical axis is declination, the exact match to latitude on the Earth. The horizontal line at 00°00′ is the celestial equator, a projection of the Earth’s equator on the sky. The diagonal line that the Sun appears to travel on is the ecliptic, the plane of the Earth’s orbit. Due to the tilt of the Earth’s axis it is inclined by 23.5° to the celestial equator. The horizontal values mark right ascension, the celestial analog of longitude. One hour equals 15°. Since the Earth rotates, the right ascension that is on one’s meridian, the north-south line passing through the zenith, is best kept track of by using a clock. A clock that runs 3 minutes 56 seconds fast a day. We call that a sidereal clock. Created using Cartes du Ciel (Sky Chart) and GIMP.
09/18/2020 – Ephemeris – A closer look at Cepheus the king’s most famous star
This is Ephemeris for Friday, September 18th. Today the Sun will be up for 12 hours and 20 minutes, setting at 7:46, and it will rise tomorrow at 7:27. The Moon, 1 day past new, will set at 8:52 this evening.
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 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 event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Cassiopeia and Cepheus finder animation looking in the northeast at 9 pm or about an hour after sunset in mid-September. Created using Stellarium and GIMP.
Delta Cephei (circled) finder for mid-September at 9 pm or about an hour after sunset looking northeast. The brighter stars are marked by their Bayer Greek letters. Numerical designations are Flamsteed numbers. Created using Cartes du Ciel (Sky Chart).
Light Curve of Delta Cephei. The pulsation period is 5.367 days. Credit: ThomasK Vbg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=13887639
09/17/2020 – Ephemeris – Finding Cassiopeia the queen and Cepheus the king
This is Ephemeris for Thursday, September 17th. Today the Sun will be up for 12 hours and 24 minutes, setting at 7:48, and it will rise tomorrow at 7:25. The Moon is new today, and won’t be visible.
The stars of the autumn skies are slowly replacing the summer stars from the east. Look midway up in the northeastern sky in the evening and you can find the W shaped constellation of Cassiopeia the queen. Cassiopeia is so far north that it never sets for us in Michigan. It is opposite the pole star Polaris from the handle of Big Dipper. There’s a dim star that appears above the middle star of the W which turns it into a very crooked backed chair, Cassiopeia’s throne. Above and left of Cassiopeia is a dim upside down church steeple shaped constellation of Cepheus the king, her husband. The Milky Way flows through Cassiopeia toward the northeastern horizon. She is a character in an autumn star story with five other constellations.
For my retelling of the Greek myth that links these autumn constellations click here.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Cassiopeia and Cepheus finder animation looking in the northeast at 9 pm or about an hour after sunset in mid-September. Created using Stellarium and GIMP.
09/16/2020 – Ephemeris – Let’s look at a the naked-eye planets for this week. Plus thoughts on phosphine in Venus’ atmosphere
This is Ephemeris for Wednesday, September 16th. Today the Sun will be up for 12 hours and 27 minutes, setting at 7:50, and it will rise tomorrow at 7:24. The Moon, 1 day before new, will rise at 7:20 tomorrow morning.
Let’s look at a the naked-eye planets for this week. Jupiter and Saturn are both low in the southern sky at 10 pm. Jupiter is the very bright one. To the left of it will be the somewhat dimmer Saturn. They are now seemly to close a tiny bit since Jupiter is resuming its eastward motion, and they will cross paths in December. Jupiter will set first at 1:37 tomorrow morning with Saturn following at 2:19. The next planet visible will be Mars which will rise at 9:15 pm. Its now down to 41.3 million miles (66.6 million kilometers) away, as the Earth slowly overtakes it at the rate of about 2.1 million miles (3.1 million kilometers) the last week as the Earth begins to pull abreast of it. Brilliant Venus will rise at 3:42 am as it retreats toward the Sun.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Planets visible at 10 pm or about 2 hours after sunset with the zodiacal constellations tonight September 16, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.
Mars, Venus and the zodiacal constellations and Orion at 6 am or an hour and a half before sunrise tomorrow morning September 17, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.
The planets as seen in a telescope (north up) with the same magnification for the night of September 16/17, 2020. Times of the display are: Jupiter and Saturn, 10 pm; Mars, Midnight; Venus, 6 am. Apparent diameters: Jupiter, 42.31″; Saturn, 17.59″, rings, 40.96″. Mars, 21.24″, and Venus 17.09″. Mars also displays an enlargement showing surface detail. The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on September 16, 2020. The night ends on the left with sunrise on the 17th. Click on the image to enlarge. Created using my LookingUp program.
Breaking planet news
Yesterday there were a rash of posts on social media and other sources to the effect “Is there life on Venus?” This was due to an article released in Nature Astronomy that the compound phosphine was discovered in the Venusian atmosphere. Phosphine (PH3) on the Earth, at least, is mostly produced by life processes. I’m still absorbing all of this so check out articles by Dr. Phil Plait (The Bad Astronomer) and Steven Novella (Skeptic’s Guide to the Universe) for less technical takes on the discovery.
Venus is the subject of two of the four proposed discovery program missions that NASA announced this past June. one of them DAVINCI+ will be looking at the atmospheric chemistry and might get a boost and some tweaks due to the phosphine discovery. DAVINCI+ will drop through the atmosphere. The best mission for this would be a balloon floating in the Venusian atmosphere above the sulfuric acid clouds. The Russians did it in 1986. Anyway any mission to Venus is many years away.
I’ll have more for the Ephemeris program itself when I know more.
09/15/2020 – Ephemeris – The dolphin and the arrow, small summer constellations
This is Bob Moler with Ephemeris for Tuesday, September 15th. Today the Sun will be up for 12 hours and 30 minutes, setting at 7:52, and it will rise tomorrow at 7:23. The Moon, 2 days before new, will rise at 6:01 tomorrow morning.
Located below the eastern edge of the Summer Triangle of three of the brightest stars in the sky, which is nearly overhead in our sky at 10 p.m., is the tiny constellation of Delphinus the dolphin. Delphinus’ 6 stars in a small parallelogram with a tail, really does look like a dolphin leaping out of the water. The parallelogram itself has the name Job’s Coffin. The origin of this asterism or informal constellation is unknown. Of the dolphin itself: the ancient Greeks appreciated this aquatic mammal as we do, and told stories of dolphins rescuing shipwrecked sailors. There’s another tiny constellation to the right of Delphinus, Sagitta the arrow a small thin group of 5 stars, which represents Cupid’s dart.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Delphinus and Sagitta finder animation. Created using Stellarium and GIMP.
09/14/2020 – Ephemeris – Not exactly a mermaid
This is Bob Moler with Ephemeris for Monday, September 14th. Today the Sun will be up for 12 hours and 33 minutes, setting at 7:54, and it will rise tomorrow at 7:22. The Moon, 3 days before new, will rise at 4:42 tomorrow morning.
Nearly 2000 years ago the southernmost of the constellations of the zodiac was Capricornus which is a water goat. That’s why the latitude on the Earth where the Sun is overhead on the winter solstice is called the Tropic of Capricorn. Not any more, Sagittarius, one constellation west past Jupiter and Saturn this year, has that honor today. Actually Capricornus does need the press. It’s large, but made up of dim stars. To me it looks like a 45 degree isosceles triangle, long side up, but which all the sides are sagging. The constellation is found low in the south-southeast at 10 p.m. The image that is supposed to be represented by the stars is that of a goat whose hind quarters are replaced by a fish’s tail, not a mermaid but a mergoat.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Capricornus finder animation for September 14, 2020 at 10 pm for western Michigan. Note that the Teapot of Sagittarius is pouring its contents on the southwestern horizon is to the right. Created using Stellarium and GIMP.
Important seasonal latitudes on the Earth. Source: worldatlas.com
