Archive
07/20/2020 – Ephemeris – Comet NEOWISE tonight and the spacecraft that discovered it
This is Ephemeris for Monday, July 20th. Today the Sun will be up for 15 hours and 4 minutes, setting at 9:21, and it will rise tomorrow at 6:17. The Moon is new today, and won’t be visible.
With the Moon being new today, that means that by the end of the week it will interfere some with spotting Comet NEOWISE. Tonight the comet will be below the lowest star in the bowl of the Big Dipper. Its head should be as bright as the dimmest star of that dipper (the one that joins the handle to the bowl). Where did the comet’s name come from? Back in 2009 NASA launched the Wide-field Infrared Survey Explorer (WISE) spacecraft to survey the infrared sky. It was a telescope built inside a cylinder of solid hydrogen to keep it near absolute zero. In 10 months the hydrogen sublimated away and the project ended. They found that even a warmed up WISE could still find asteroids, so began the Near Earth Object or NEOWISE program.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet NEOWISE Finder for 11 pm tonight July 20, 2020. Created using Stellarium.
07/17/2020 – Ephemeris – Viewing Comet C/2020 F3 (NEOWISE) this weekend
This is Ephemeris for Friday, July 17th. Today the Sun will be up for 15 hours and 9 minutes, setting at 9:23, and it will rise tomorrow at 6:14. The Moon, 3 days before new, will rise at 4:01 tomorrow morning.
With Comet NEOWISE visible low in the northwest around 11 pm, one might wonder just what a comet is. Comets in general scared the crap out of the peoples of Eurasia. Comets gate crashed the perfect order of the cosmos they had thought up and supposedly caused all sorts of mayhem. As far as I’m concerned this comet is the one bright spot so far this year. A comet is mostly nothing. NEOWISE has a solid nucleus which is perhaps 3 miles (5 km) in diameter and a tail of many million of miles (km) long. If that nucleus was rock instead of frozen gasses, water and pebbles one would need a good sized telescope to spot it. Instead the gasses evaporate creating a giant head that rivals Jupiter in size and a tail all considered pretty good vacuum by earthly standards.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
An animation showing the position of Comet NEOWISE at 11 pm (or approximately an hour and a half after sunset if you’re not from Northern Michigan) for Friday, Saturday and Sunday evenings July 17-19, 2020. Created using Stellarium.
Update
Comet NEOWISE from backyard over tall shrubbery 11:18 pm July 16, 2020. I didn’t have time to focus properly which actually accentuates the stars.
07/16/2020 – Ephemeris – Comet NEOWISE’ orbit and path in our skies
This is Ephemeris for Thursday, 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, half way from last quarter to new, will rise at 3:20 tomorrow morning.
Comet NEOWISE is now visible in the northwest at about 11:00 pm. It doesn’t fare too well in twilight. The tail will be near vertical but tilted a bit to the right. The comet’s orbit is tilted about 40 degrees to the Earth’s orbital plane and it is traveling opposite the traffic flow of the planets and asteroids of the solar system. It came from the south and is reaching its northern most position before heading back to the south. It is actually circumpolar now, meaning it is far enough north in our sky so it doesn’t set for those of us in the Grand Traverse region for another 6 days. Its low point will be just scraping the northern horizon. It is still visible in the morning in the northeast, but the evening time is now the best time to view it.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet 2020 F3 NEOWISE at 11 pm July 16, 2020, approximately an hour and a half after sunset. Created using Stellarium.
C/2020 F3 (NEOWISE) orbit. Comet position at July 16 at 8 pm EDT: Earth distance 0.765 au, Sun distance 0.479 au. Credit JPL Small-Body Browser
07/10/2020 – Ephemeris – The constellation Cygnus the swan
This is Bob Moler with Ephemeris for Friday, July 10th. Today the Sun will be up for 15 hours and 20 minutes, setting at 9:28, and it will rise tomorrow at 6:08. The Moon, 2 days before last quarter, will rise at 12:52 tomorrow morning.
Fairly high in the east at 11 p.m. 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 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 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 to a couple more stars each.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
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.
07/09/2020 – Ephemeris – The constellation of Lyra the harp
Jul 9. This is Bob Moler with Ephemeris for Thursday, 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, 3 days before last quarter, will rise at 12:30 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. It is a pure white star and serves as a calibration star for color and brightness. 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 event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Lyra as a tortoise shell harp. Created using Stellarium and free clip art.
07/07/2020 – Ephemeris – New Comet NEOWISE (C/2020 F3) is visible in the morning
This is Ephemeris for Tuesday, July 7th. Today the Sun will be up for 15 hours and 24 minutes, setting at 9:29, and it will rise tomorrow at 6:06. The Moon, 2 days past full, will rise at 11:37 this evening.
Comet C/2020 F3 (NEOWISE) is visible in the morning now, and quite bright. At 5 am in twilight it will be very low in the northeast tomorrow morning, below the bright star Capella. I’ve seen a photograph of it showing a tail. Over the next week it will be moving northward along the horizon at 5 am and fading as it goes. Then it will become visible in the evening sky next week. It is best seen in binoculars, though it can be spotted with the naked eye. One needs a low northeastern horizon. That’s the problem with comets: they’re brightest when close to the Sun, and can be seen best only when the Sun isn’t up. So that leaves morning or evening twilight, unless they are a huge comet like Hale-Bopp of 23 years ago that doesn’t get close to the Sun.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet NEOWISE starting at 5 am February 8, 2020. Every second date has month-day and predicted magnitude. The sky will be a bit higher each morning. Created using Cartes du Ciel (Sky Charts)
07/06/2020 – Ephemeris – The southernmost star of the Summer Triangle, Altair
This is Bob Moler with Ephemeris for Monday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 1 day past full, will rise at 11:02 this evening.
The southernmost star of the Summer Triangle is Altair, high in the east-southeast. The other two stars of the triangle are Vega nearly overhead in the east, and Deneb high in the east-northeast. Altair is the closest of the three at a distance of 16.7 light years away. One light year is nearly 6 trillion miles. Altair is 10 times the brightness of the Sun. If seen at Altair’s distance, the Sun would only be as bright as one of the two stars that flank it. What is rather different about Altair is its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in about 9 hours, The CHARA Interferometer at Mt. Wilson has actually imaged its squashed disk in the infrared. Our Sun’s a slow poke, taking nearly a month to rotate once.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Summer Triangle. Created using Stellarium.
Lines added to show the rotation axis. Credit: Zina Deretsky, National Science Foundation.
06/26/2020 – Ephemeris – The stars known as the Horse and Rider
Jun 26. This is Bob Moler with Ephemeris for Friday, June 26th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:32, and it will rise tomorrow at 5:59. The Moon, 2 days before first quarter, will set at 1:28 tomorrow morning.
The most interesting star in the Big Dipper is Mizar and its dim companion Alcor. It is the second star from the end of the handle, where the bend in the handle takes place. Folks with good vision can see the dimmer star right next to Mizar. In ancient times it was used as an eye test for visual acuity for warriors. As such it was known as the “Horse and the Rider”. Mizar is second magnitude, in the second rank of star brightness invented by the Greek astronomer Hipparchus in the 2nd century BC. He ranked stars in 6 classes, from first magnitude for the brightest to 6th for the dimmest visible to the naked eye. Alcor comes in at 4th magnitude. It does suffer a bit by being very close to Mizar which is 6 times brighter.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mizar finder animation for the Big Dipper’s orientation in late June at 11 pm where I live or an hour and a half after sunset. Created using Stellarium and GIMP.
Mizar and Alcor as they might appear in a telescope. Mizar is a binary star in a telescope. The other star in the field is apparently a background star. The brighter star of Mizar is Mizar A, while the dimmer is Mizar B. It turns out that Mizar A and B plus Alcor are all spectroscopic binaries, meaning the companion stars are too close to resolve in telescopes, but whose motion shows up in the spectra of the stars. Mizar and Alcor are around 80 light years away. Created using Stellarium.
06/24/2020 – Ephemeris – Let’s look at the naked-eye planets for this week
This is Bob Moler with Ephemeris for Wednesday, June 24th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 3 days past new, will set at 12:27 tomorrow morning.
Let’s look at the naked-eye planets for this week. Jupiter now rises in the evening, tonight it’s at 10:42 pm in the east-southeast. Saturn will rise 18 minutes later at 11pm right behind Jupiter. Mars, is stretching its lead left of Saturn and will rise at 1:36 am in the east. Its now down to 83.4 million miles (134.3 million km) away, as the Earth slowly overtakes it at the rate of about 4 million miles (6.4 million km) a week. Jupiter and Saturn will be hanging out between Sagittarius and Capricornus this year while Mars is slowing its rapid eastward motion now two constellations over in Pisces. Finally, Venus will rise at 4:26 am in the east-northeast low in the twilight as our Morning Star.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon as seen through binoculars or small telescope tonight June 24, 2020. Note earthshine on the night side of the Moon. Created using Stellarium.
Jupiter & Saturn at midnight. Note the Teapot of Sagittarius to the right of Jupiter and the stars of Scorpius including Antares farther right. Click on the image to enlarge. Created using Stellarium.
Four of the five naked-eye planets stretched out on this panorama from northeast to southwest at 5 am tomorrow morning June 25, 2020. Click on the image to enlarge. Created using Stellarium.
The planets as seen in a telescope (north up) with the same magnification tomorrow morning June 25, 2020. Apparent diameters: Jupiter, 46.96″; Saturn, 18.28″, rings, 42.58″, Mars, 10.99″, and Venus 47.10″. Mars also shows an enlargement showing surface detail. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge. 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 June 24, 2020. The night ends on the left with sunrise on the 25th. The closeness of Jupiter and Saturn in the morning sky unfortunately overlays planets and labels. Click on the image to enlarge. Created using my LookingUp program.
06/11/2020 – Ephemeris – The Moon passes Mars starting tomorrow morning
This is Ephemeris for Thursday, June 11th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, 2 days before last quarter, will rise at 2:04 tomorrow morning.
In the morning sky tomorrow and Saturday morning the Moon will be passing Mars. Actually you’ll see a before and after shot of them because the Moon’s passage south of Mars will occur about 6 pm tomorrow evening when we can’t see them. Mars is getting brighter as we, on the Earth approach it. It is also getting larger in telescopes. On Wednesdays on this blog besides showing where the planets are, I show what they might look like in a small telescope. Until this week Mars appeared too small for me to show detail on Mars. However it is now large enough to maybe see a polar cap and some other detail depending on telescope size. Mars will double its apparent size between now and October.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Moon and Mars animation for 5 am Friday June 12, 2020 and 4:56 am Saturday June 13th. The Jump between of 23 hours, 56 minutes and 4 seconds is the Earth’s sidereal day, the true period of its rotation in relation to the stars. Note that the few stars visible do not move, but Mars and the Moon do. Created using Stellarium and GIMP.
