Archive
04/21/2020 – Ephemeris – The Lyrid Meteor Shower will reach its peak after midnight tonight
This is Ephemeris for Tuesday, April 21st. Today the Sun will be up for 13 hours and 48 minutes, setting at 8:36, and it will rise tomorrow at 6:45. The Moon, 1 day before new, will rise at 6:58 tomorrow morning.
The Lyrid meteor shower will reach its peak tomorrow morning at around 2 a.m. The Moon will be new tomorrow so it won’t interfere. The radiant point, from which the meteor seem to come is between the constellation Lyra the harp for which they are named with its bright star Vega and Hercules. The numbers of meteors seen in an hour could be between 12 and 20. The Lyrids are caused by the debris left when a comet last seen in 1861, crossed Earth’s orbit as Comet Thacher. Speaking of comets, a new comet named SWAN was discovered a month ago. It was detected by with the Solar Wind An-iso-tropies camera or SWAN aboard the Solar and Heliospheric Observatory or (SOHO) spacecraft. We’ll follow Comet SWAN as it approaches the Sun next month.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
An animation Looking east at 2 a.m. April 22, 2020 toward Lyra, and Hercules with the Lyrid meteor radiant. The named stars are the stars of the Summer Triangle. Click on the image to enlarge. The meteors will appear all over the sky, but Lyrid meteors can be back traced to the radiant point. Created using Stellarium and GIMP.
04/20/2020 – Ephemeris – The Little King Star
This is Ephemeris for Monday, April 20th. Today the Sun will be up for 13 hours and 45 minutes, setting at 8:34, and it will rise tomorrow at 6:47. The Moon, 2 days before new, will rise at 6:37 tomorrow morning.
The brightest star in the constellation Leo, which is high in the south these evenings is Regulus, whose name means “Little King”. It is appropriate due to its position in the heart of the king of beasts Leo the lion. Regulus is dead last in brightness of the 21 first magnitude stars, the brightest night-time stars. Even so, it is much brighter than the Sun. It is 79 light years away. The Sun would require a telescope to be spotted at that distance. Regulus appears to be a quadruple star system. The bright star itself is really two stars with a bright star orbited by a much dimmer star every 40 days. There are two dimmer stars much further out that share Regulus’ motion through space. There are an infinite variety of star system arrangements in the galaxy and beyond.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The naked eye stars of Leo, including Regulus at 9:30 p.m. April 20, 2020. Note that Algieba is a binary star that can be seen in small telescopes. The yellow line that passes Regulus is the ecliptic the apparent path of the Sun. The Moon and planets also hang out near that line. Created using Cartes du Ciel (Sky Charts).
04/17/2020 – Ephemeris – More on Comet ATLAS
One of the problems that can happen when you record programs several days before they are aired is that events can get ahead of you. Comet ATLAS is disintegrating and won’t get any brighter than it already is. This program was written after I read reports that the comet had faded but the full ramifications of the fading were not known.
This is Bob Moler with Ephemeris for Friday, April 17th. Today the Sun will be up for 13 hours and 36 minutes, setting at 8:31, and it will rise tomorrow at 6:52. The Moon, 3 days past last quarter, will rise at 5:32 tomorrow morning.
Lets talk more about Comet C/2019 Y4 (ATLAS). For this program I talk about celestial sights visible to the naked-eye or are easily found in binoculars. Each program script is posted on this blog usually with images and charts. The blog postings are generally illustrated. Anyway, it seems that Comet ATLAS is breaking up. With the Neil Sedaka’s 1960 song “Breakin up is hard to do” to the contrary, for comets breaking up is quite easy. They are porous assemblages of bits of dust, pebbles and frozen gasses. It is already most likely a chip off the old block.. er comet. It follows the same orbit as the Great Comet of 1844. Both of these could be parts of an even larger comet passing the Sun 6 or maybe even 12 thousand years ago.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet ATLAS C/2019 Y4 showing two nuclei on April 15, 2020. Credit: Jose De Queiroz and Michael Deyerler from Switzerland’s public Mirasteilas Observatory. Copied from Spaceweather.com. The streaks are stars as the telescope was tracking the comet during the exposure.
An even newer discovered comet may make it to naked-eye visibility late next month, if it holds together. I’ll talk about Comet C/2020 F8 (SWAN) next Tuesday.
04/16/2020 – Ephemeris – Comet C/2019 Y4 (ATLAS)
One of the problems that can happen when you record programs several days before they are aired is that events can get ahead of you. Comet ATLAS is disintegrating and won’t get any brighter than it already is. This program was written and recorded before I realized that it was falling apart.
This is Bob Moler with Ephemeris for Thursday, April 16th. Today the Sun will be up for 13 hours and 33 minutes, setting at 8:29, and it will rise tomorrow at 6:54. The Moon, 2 days past last quarter, will rise at 5:05 tomorrow morning.
There’s a new comet about, which may reach naked-eye visibility next month. It is comet C/2019 Y4 (ATLAS). It was discovered three days after Christmas last year by the apocalyptic sounding Asteroid Terrestrial-Impact Last Alert System (ATLAS), run out of the University of Hawai’i. Despite the name of the search system the comet they snagged will not come close to the Earth, contrary to some misleading posts on social media. Comet ATLAS, yes it’s an acronym, could reach first magnitude when it’s close to the Sun at the end of May, but will be in the bright evening twilight by then. I don’t think that it can be picked up in binoculars yet. I’ll have more about it tomorrow.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
This image starts at 10 p.p. looking north-northwest. Also plotted was Comet PANSTARRS. I removed some of its labels that plotted over the ATLAS labels. The labels have the comet name, month-day and magnitude. Any magnitude value greater than 6.0 is invisible to the naked-eye. We were hoping that ATLAS would get a lot brighter. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).
04/15/2020 – Ephemeris – Let’s look at the naked-eye planets for this week
This is Bob Moler with Ephemeris for Wednesday, April 15th. Today the Sun will be up for 13 hours and 30 minutes, setting at 8:28, and it will rise tomorrow at 6:55. The Moon, 1 day past last quarter, will rise at 4:34 tomorrow morning.
Let’s look at the naked-eye planets for this week. Venus is our evening star shining brightly in the west above the Pleiades. It will set at 12:37 a.m. The rest of the planet action is in the morning sky where there are three planets nearly evenly spread out in the southeast. Bright Jupiter will rise first at 3:21 a.m. Followed by Saturn at 3:38 a.m. Mars, left of Saturn and nearest to the Moon tomorrow morning, will rise at 4:14 a.m. It’s now down to 125 million (201 million km) miles away, as the Earth slowly overtakes it at the rate of about 5 million miles (8 million km) a week. Mars will be closest to us in October at about 39 million miles (62 million km). Not quite as close as it was 2 years ago, but closer than it will get for the next 15 years.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus in twilight at 9 p.m. tonight April 15, 2020, a half hour or so after sunset. Click on the image to enlarge. Created using Stellarium.
The Morning planets and the Moon at 6 a.m. tomorrow April 16, 2020. Click on the image to enlarge. Created using Stellarium.
The crescent Moon as it might be seen in binoculars at 6 a.m. tomorrow April 16, 2020. Created using Stellarium.
The planets as seen in a telescope with the same magnification. Venus in the evening and Jupiter and Saturn in the morning on the night of April 15/16, 2020. Apparent diameters: Venus, 31.01″; Jupiter, 38.84″; Saturn, 16.53″, rings, 38.51″. Mars at 6.99″ won’t be added until it reaches 10″. 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 April 15, 2020. The night ends on the left with sunrise on the 16th. The planet traffic jam in the morning sky unfortunately overlays planets and labels. Click on the image to enlarge. Created using my LookingUp program.
04/14/2020 – Ephemeris – The Moon will be hanging out with the morning planets tomorrow
This is Ephemeris for Tuesday, April 14th. Today the Sun will be up for 13 hours and 28 minutes, setting at 8:27, and it will rise tomorrow at 6:57. The Moon, at last quarter today, will rise at 3:56 tomorrow morning.
Tomorrow morning the Moon will be in the midst of passing the three morning planets, from right to left: Jupiter, Saturn and Mars. Specifically, the last quarter Moon will be below Saturn at 6 a.m. Mars is traveling east rapidly. Its rise times decrease by only two minutes a day compared to the 4 minutes a day for the stars, so it won’t enter the evening sky until October, while Jupiter and Saturn will enter the evening sky in July. A planet is considered to be in the morning sky if it rises after sunset, and in the evening sky if it rises before sunset. Rising in the morning is definitely after sunset. The dividing point is when a superior* planet is at opposition from the Sun when it enters the evening sky, or in conjunction with the Sun when it enters the morning sky.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
* Superior planets have orbits outside the Earth’s orbit: Mars, Jupiter, Saturn, Uranus and Neptune.
Addendum
Morning planets and Moon in the south-southeast tomorrow morning at 6 a.m. April 15, 2020. Click on image to enlarge. Created using Stellarium.
04/13/2020 – Ephemeris – The story of Callisto and Arcas or Ursa Major and Boötes
This is Ephemeris for Monday, April 13th. Today the Sun will be up for 13 hours and 25 minutes, setting at 8:26, and it will rise tomorrow at 6:59. The Moon, 1 day before last quarter, will rise at 3:09 tomorrow morning.
Appearing mid way up the sky in the east at 10 p.m. is the kite shaped constellation of Boötes the herdsman. The bright star Arcturus is at the bottom-right of the kite, pointed to by the arc of the handle of the Big Dipper, above it. In one Greek myth Boötes represents a young hunter named Arcas, son of Callisto, a beautiful young lady who had the misfortune of being loved by Zeus the chief of the Greek gods. Zeus’ wife Hera, found out about the affair, and since she couldn’t punish Zeus, turned the poor woman into an ugly bear. Arcas, unaware of the events surrounding his mother’s disappearance in his youth was about to kill the bear when Zeus intervened and placed them both in the sky to save her. To this day Boötes continues to chase the Great Bear, Ursa Major, around the pole of the sky each night.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Bootes and Ursa Major aka Arcas chasing Callisto around the pole of the sky. Created using Stellarium.
Arcas about to slay the bear by the 17th century artist Baur. Source: University of Virginia Electronic Text Center
04/10/2010 – Ephemeris – The constellations of Ursa Major and Ojiig
This is Ephemeris for Good Friday, Friday, April 10th. Today the Sun will be up for 13 hours and 15 minutes, setting at 8:22, and it will rise tomorrow at 7:04. The Moon, 3 days past full, will rise at 11:54 this evening.
The constellation of Ursa Major, or great bear was well-known to the ancient Greeks and Native Americans. Today, however, many of us can recognize only part of it as the Big Dipper. The whole bear can be easily seen only in a dark sky, at 10 p.m. it’s high in the northeast with feet to the south. The stars in front of the bowl are the front part of his body and head. The bowl of the Big Dipper is his rump, and the handle his long tail. The Native Americans, saw those three stars as three hunters following the bear. The tribes of the Great Lakes region saw it as the Fisher or Ojiig , who brought summer to the Earth. These stars here do make a convincing bear, except for the tail, when seen on a dark night. The weasel-like Fisher fits the stars completely.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Big Dipper/Great Bear/Fisher as seen by western and Anishinaabe people. Created using Stellarium and GIMP.
The constellation art is part of the latest versions of Stellarium. Ojibwe (Anishinaabe) constellation art by Annette S Lee and William Wilson from Ojibwe Sky Star Map Constellation Guide, ISBN 978-0-615-98678-4.
Here’s the story of how the Fisher brought summer to the Earth: https://bobmoler.wordpress.com/2012/10/11/the-story-of-the-fisher-star/
04/09/2020 – Ephemeris – How to find the constellation of Leo the lion
This is Ephemeris for Thursday, April 9th. Today the Sun will be up for 13 hours and 12 minutes, setting at 8:21, and it will rise tomorrow at 7:06. The Moon, 2 days past full, will rise at 10:36 this evening.
At 10 p.m. the spring constellation of Leo the lion will be high in the south-southeast. It can be found by locating the Big Dipper high in the northeast and imagining that a hole were drilled in the bowl to let the water leak out. It would drip on the back of this giant cat. The Lion is standing or lying facing westward. His head and mane are seen in the stars as a backwards question mark. This group of stars is also called the sickle. The bright star Regulus is at the bottom, the dot at the bottom of the question mark. A triangle of stars, to the left of Regulus, is the lion’s haunches. Leo contains some nice galaxies visible in moderate sized telescopes. The stars in Leo’s part of the sky are fewer than those in the winter sky.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Leaky Big Dipper drips on Leo. Created using my LookingUp program.
Ursa Major with the Big Dipper in her hind end and Leo. Created using Stellarium and GIMP.
04/08/2020 – Ephemeris – Morning planets are not practicing social distancing
Note: It seems the title is appropriate to our current predicament even though I hadn’t thought about it when I wrote and recorded the radio script that follows last Sunday.
This is Ephemeris for Wednesday, April 8th. Today the Sun will be up for 13 hours and 9 minutes, setting at 8:19, and it will rise tomorrow at 7:08. The Moon, 1 day past full, will rise at 9:16 this evening.
Let’s look at the naked-eye planets for this week. Venus is our evening star shining brightly in the west above the Pleiades. It will set at 12:33 a.m. The rest of the planet action is in the morning sky where there are three planets nearly evenly spread out in the southeast. Bright Jupiter will rise first at 3:46 a.m. Followed by Saturn at 4:05 a.m. Mars, left and below Saturn will rise at 4:27 a.m. It’s now as bright as a first magnitude star because it’s down to 130 million miles (209 million km) away, as the Earth slowly overtakes it at the rate of about 5 million miles (8 million km) a week. It’s brighter than the star Antares in the southwest. Mars will be closest to us in October, which makes a good time to launch spacecraft to it few months before then.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus in the evening with the setting winter stars including those in Orion and Taurus at 10 p.m. April 8, 2020. Click on the image to enlarge. Created using Stellarium.
The Moon as it might be seen in binoculars at 10 p.m. April 8, 2020. Created using Stellarium.
The morning planets and the southern summer stars in the moonlight at 6 a.m. April 9, 2020. The bright star on the right is Antares. Click on the image to enlarge. Created using Stellarium.
The planets as seen in a telescope with the same magnification. Venus in the evening and Jupiter and Saturn in the morning on the night of April 8/9, 2020. Apparent diameters: Venus, 28.21″; Jupiter, 38.00″; Saturn, 16.34″, rings, 38.07″. Mars at 6.72″ won’t be added until it reaches 10″. 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 April 8, 2020. The night ends on the left with sunrise on the 9th. The planet traffic jam in the morning sky unfortunately overlays planets and labels. Click on the image to enlarge. Created using my LookingUp program.
