Archive
06/23/2023 – Ephemeris – Sun and Star Party scheduled for tomorrow at the Sleeping Bear Dunes
This is Ephemeris for Friday, June 23rd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 3 days before first quarter, will set at 1:11 tomorrow morning.
Tomorrow the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society will host a Sun and Star Party at the Dune Climb area of the park. There will be a solar viewing period from 6 pm to 8 pm. The society has two hydrogen alpha solar telescopes to view the Sun’s chromosphere and prominences. Plus some members also have solar scopes also white light filtered telescopes to view sunspots on the face of the Sun. Night viewing will start at 10 pm with the Moon and Venus featured, along with the brighter telescopic wonders of early summer. The park rangers will leave at midnight, but society members can stay later to view the fainter wonders in the darkened sky. All this will happen only if clouds permit.
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
The Dune Climb is not the place to view the spectacular sunset. The best place is from the Lake Michigan Overlook stop on Pierce Stocking Scenic Drive.
06/22/2023 – Ephemeris – The lunar seas on tonight’s Moon
This is Ephemeris for Thursday, June 22nd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, halfway from new to first quarter, will set at 12:51 tomorrow morning.
The crescent Moon tonight reveals two large seas. Astronomers using the first telescopes thought the darker flat areas on the moon may actually be filled with water. It turns out that they are flat lava plains, and since most of them are roughly circular, may be gigantic craters from impacts of asteroids. Examination of rocks brought back by the Apollo astronauts over 50 years ago suggest the age of the seas at around 4 billion years. This suggests some kind of disruption in the solar system, called the Late Heavy Bombardment. The reason the Earth does not have these scars is due to plate tectonics and the weathering of wind and water. The Moon has none of these, so it preserves the damage done to it.
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
Late Heavy Bombardment (Based on my August 4, 2022 post)
There are even more and larger seas on the east half of the Moon, as we see it. Most were created about 3.9 billion years ago by asteroid strikes. The same thing happened to the Earth, but plate tectonics destroyed the evidence. Not so on the Moon. The result, many planetary scientists think, was the Late Heavy Bombardment, caused by the shifting orbits of mainly Saturn, Uranus and Neptune that disrupted the smaller asteroids, and sending them careening through the solar system.
06/21/2023 – Ephemeris – Let’s find out where the naked-eye planets have wandered off to this week
This is Ephemeris for Wednesday, June 21st. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 3 days past new, will set at 12:27 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week. Looking below the horizon we see our planet, which will reach the June solstice and the beginning of summer in the northern hemisphere later this morning (10:58 am EDT, 14:58 UT). Venus is our blazing Evening Star seen in the west all evening. It will still set after midnight, but barely. Tonight it is seen below the Moon. The red planet Mars is seen left of and a bit higher than Venus by four and a half degrees, or a bit less than half the width of one’s fist held at arm’s length. Venus is closing the gap between them, but will never quite reach Mars while they are in the evening sky. The closest they will get is three and a half degrees or 7 moon diameters apart, before Venus pulls back toward the Sun faster than Mars will. Both Mars and Venus are in Cancer. In the morning, Saturn will be visible low in the south-southeast at 5 am. Jupiter will be low in the east at that hour.
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
06/20/2023 – Ephemeris – Summer starts tomorrow!
This is Bob Moler with Ephemeris for Tuesday, June 20th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 2 days past new, will set at 11:58 this evening.
Tomorrow is the day of the longest daylight hours, the summer solstice. The exact time of the summer solstice will occur at 10:58 am. One really can’t tell where the Sun is against the constellations and its eastward motion along the ecliptic because when the Sun’s out the sky is blue and the stars are invisible. However the ancients could notice that the Sun changed its height in the South over the year and the summer solstice was the time that the Sun was highest in the sky. The word solstice means “Sun standstill”. All through winter and spring the Sun has been moving northward in the sky at local noon. This has slowed down and tomorrow it will stop. After that it will begin to descend in the South at local noon until the winter solstice on December 21st.
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
06/16/2023 – Ephemeris – Twilight is longer near the summer solstice
This is Ephemeris for Friday, June 16th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:30, and it will rise tomorrow at 5:56. The Moon, 2 days before new, will rise at 5:04 tomorrow morning.
Not only does the Sun set later this time of year, but twilight lasts longer too. As of tonight the end of astronomical twilight, when the last vestiges of twilight are gone is, for the Traverse City/Interlochen area, 12:01 am, That’s two and a half hours of evening twilight. I feel that for most purposes that the end of nautical twilight, when navigators on ships could no longer see the horizon for their sextant readings, is dark enough to view most stars, and brighter objects beyond the solar system, what we call deep sky objects. That happens at 10:56 pm, or about an hour and a half after sunset. Twilight of both kinds are a third shorter around the equinoxes. These times are dependent on our latitude, and the Sun’s declination which is equivalent to latitude.
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
Check out my September 27, 2018 post about the different twilight periods.
06/14/2023 – Ephemeris – Let’s find out where the naked-eye planets have wandered off to this week
This is Bob Moler with Ephemeris for Flag Day, Wednesday, June 14th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, half way from last quarter to new, will rise at 3:59 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week. Venus is our blazing Evening Star seen in the west all evening. It will set after midnight. The red planet Mars is seen left of and a bit higher than Venus by six and a half degrees, or a bit more than half the width of one’s fist held at arm’s length. Venus is closing the gap between them, but will never quite reach Mars while they are in the evening sky. The closest they will get is three and a half degrees or seven moon diameters apart, before Venus pulls back toward the Sun faster than Mars will. Both Mars and Venus are in Cancer. In the morning, Saturn will be visible low in the south-southeast at 5 am. Jupiter will be very low in the east at that hour.
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
06/13/2023 – Ephemeris – Messier 13, the Great star cluster in Hercules
This is Bob Moler with Ephemeris for Tuesday, June 13th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 3 days past last quarter, will rise at 3:34 tomorrow morning.
About a third of the way between the bright stars Vega which is high in the east and Arcturus, high in the south, can be found the Keystone of Hercules, a four-star box wider at the top than at the bottom. Along the right edge, a third of the way down is what looks like a faint star to someone with really good vision. In binoculars the star becomes fuzzy. One needs a larger telescope probably six or eight inches in diameter to begin to see some stars among the fuzziness. That is a globular star cluster containing hundreds of thousands of stars. This is the Great Hercules Globular Star Cluster. It’s beautiful if seen in a large telescope, such as the one brought out to the star parties at the Sleeping Bear Dunes, especially in August and September.
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
Dan’s image is rotated from Scott’s. The bright star at the lower left of Scott’s image is the same as the one at the lower left of Dan’s.
Globular star clusters are uniformly very old. M 13 is estimated to be between 11 and 12 billion years old, more than twice as old as our Sun and the solar system. As I say in my talks: “They don’t make them like that any more.” Globular clusters form a spherical distribution around the Milky Way galaxy with an increasing concentration toward the center. Do they reveal the original spherical shape of the galaxy before the gas and dust collapsed into the disk of the galaxy we see today? The star clusters that form today lie in the disk, and contain a few hundreds or a thousand stars. They are called open or galactic star clusters. The Pleiades is the most famous example of this type of star cluster.
06/09/2023 – Ephemeris – How to find Corona Borealis, the Northern Crown
This is Bob Moler with Ephemeris for Friday, June 9th. Today the Sun will be up for 15 hours and 29 minutes, setting at 9:27, and it will rise tomorrow at 5:57. The Moon, 1 day before last quarter, will rise at 2:13 tomorrow morning.
High in the southeast at 11 p.m. can be found a small but easily spotted constellation of Corona Borealis, the Northern Crown. It is located just east or left of the kite shaped constellation of Boötes, with its bright star Arcturus at the bottom. The Northern Crown is a three-quarters circle of stars, like a tiara, with a brighter star Alphecca at the bottom. Alphecca in Arabic means “Bright star of the broken ring of stars”. According to Greek mythology it belonged to Princess Ariadne, daughter of King Minos of Crete who helped Theseus escape from the Labyrinth of the Minotaur, only to be abandoned by him on an island. To the Native Chippewa and Ottawa of our area it is the Sweat Lodge.
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
Next Monday I will post about Hercules.
06/08/2023 – Ephemeris – The first stars that appear tonight
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06/07/2023 – Ephemeris – Let’s find where the naked-eye planets have wandered off to this week
This is Bob Moler with Ephemeris for Wednesday, June 7th. Today the Sun will be up for 15 hours and 27 minutes, setting at 9:25, and it will rise tomorrow at 5:57. The Moon, 3 days before last quarter, will rise at 1:18 tomorrow morning.
Let’s find where the naked-eye planets have wandered off to this week. Venus is our blazing Evening Star seen in the west all evening. It will set after midnight. The red planet Mars is seen left of and a bit higher than Venus by eight and a half degrees, or a bit less than the width of one’s fist held at arm’s length. Venus is closing the gap between them, but will never quite reach Mars while they are in the evening sky. The closest they will get is three and a half degrees or 7 moon diameters apart, before Venus pulls back toward the Sun faster than Mars will. Both Mars and Venus are in Cancer. In the morning, Saturn will be visible low in the southeast at 5 am, rising at 1:53 am. Jupiter is low in the east at that hour, rising at 3:57 am.
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
Bob Moler's Ephemeris Blog 