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Ephemeris: 08/30/2024 – Star party tomorrow night
This is Ephemeris for Friday, August 30th. Today the Sun will be up for 13 hours and 18 minutes, setting at 8:22, and it will rise tomorrow at 7:04. The Moon, 3 days before new, will rise at 4:11 tomorrow morning.
Weather permitting, a Star Party will be held tomorrow night at the Sleeping Bear Dunes National Lakeshore at the Dune Climb. The viewing will start at 9 pm. These events will be hosted by the park rangers and the Grand Traverse Astronomical Society, who will bring their telescopes to view the heavens, including the planet Saturn and the wonders of the summer Milky Way. The telescopes will be setup in the parking area closest to the dune. While twilight fades Saturn will be about the only object to view in the east-southeast. 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 that lie in abundance in the Milky Way.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/29/2024 – Centaur or Teapot, you decide!
This is Bob Moler with Ephemeris for Thursday, August 29th. Today the Sun will be up for 13 hours and 21 minutes, setting at 8:23, and it will rise tomorrow at 7:03. The Moon, 3 days past last quarter, will rise at 3:02 tomorrow morning.
Low in the south at 10 PM shines the heart of summer Milky Way. The constellation that’s seen there is Sagittarius which is supposed to be a centaur with a bow and arrow. We modern folk haven’t seen a centaur outside a Harry Potter movie, so we see its stars looking like a teapot, a short and stout little teapot like in the children’s song. It is tipped to the West with the Milky Way like steam rising from its spout, which is about to pour its tea on the southwestern horizon later tonight. Sagittarius is just begging to be explored with binoculars or a very low power telescope to see its myriad of stars, star clusters and nebulae. As fabulous as all this appears, we cannot see into the heart of the Milky Way for all the clouds of dust and gas in the way.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
My first guide to the constellations was Stars by Zim and Baker, a Golden Guide. I checked, it has been revised and is still available. H. A. Rey’s book is also still available.
Ephemeris: 08/28/2024 – Where are the naked-eye planets this week?
This is Ephemeris for Wednesday, August 28th. Today the Sun will be up for 13 hours and 24 minutes, setting at 8:25, and it will rise tomorrow at 7:02. The Moon, 2 days past last quarter, will rise at 1:55 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Venus might be glimpsed low in the west around 8:45 PM. It will set at 9:19. It is best seen over a very low or lake horizon. Saturn will rise at 8:52 pm, and by 10 pm will be low in the east-southeast, pretty much by itself. Saturn may look disappointing in telescopes this year since its rings are nearly edge on and appear almost as a line through the planet. Jupiter and Mars will be up in the east in the morning, and by 6 am tomorrow, Jupiter will be the brightest starlike object in the sky among the winter stars. Mars will be just below it to the left. And the waning crescent Moon below left of Mars. Jupiter will rise at 12:42 AM, with Mars rising at 1:09 AM.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/27/2024 – Space news
Sorry, about posting this late. I was working on our astronomical society article and newsletter. The article will be posted as an Ephemeris Extra in a couple of weeks. For a preview see my August 22nd post.
This is Ephemeris for Tuesday, August 27th. Today the Sun will be up for 13 hours and 27 minutes, setting at 8:27, and it will rise tomorrow at 7:01. The Moon, 1 day past last quarter, will rise at 12:55 tomorrow morning.
Let’s take a look at some space news. Today is the first day of the launch window for the SpaceX commercial mission Polaris Dawn where 4 private astronauts will ride a SpaceX Dragon capsule to the highest point astronauts have been since the Apollo days, some 1400 kilometers or 870 miles above the Earth. They will also perform the first commercial EVA or space walk. Two of the astronauts will take turns poking their body out the hatch capsule for a short period of time. They will not be free floating, but they will be connected to the capsule by foot or hand restraints.
In other news NASA has decided to bring Suni Williams and Butch Wilmore, the Boeing Starliner test astronauts, back to Earth on a Dragon capsule in February due to safety concerns.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/26/2024 – Scanning the Milky Way with binoculars
This is Ephemeris for Monday, August 26th. Today the Sun will be up for 13 hours and 30 minutes, setting at 8:29, and it will rise tomorrow at 6:59. The Moon, at last quarter today, will rise at 12:06 tomorrow morning.
Now that the Moon has left the evening sky the Milky Way dominates the sky from northeast to south-southwest. The best way to appreciate the Milky Way is with binoculars and just scan through the Milky Way as Galileo did with this primitive telescope. What he found was that the glow of the Milky Way resolved itself into individual stars, thousands upon thousands of stars, each too faint to be perceived with the naked eye. At many places in the Milky Way there are fuzzy spots. These could be nebulae, clouds of gas lit up by the stars within them, or clusters of stars not quite resolvable by binoculars, that can be studied in more detail with a larger telescope. Wandering through the Milky Way with binoculars can give hours of enjoyment.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/23/2024 – The dimmest star of the Summer Triangle is really the brightest
This is Ephemeris for Friday, August 23rd. Today the Sun will be up for 13 hours and 39 minutes, setting at 8:34, and it will rise tomorrow at 6:56. The Moon, 3 days before last quarter, will rise at 10:29 this evening.
This evening when it gets dark enough the bright star Deneb in Cygnus the swan will be very high in the east. Deneb is the dimmest star of the Summer Triangle. Of the other stars of the triangle, Vega is nearly overhead, while Altair is lower in the south-southeast. Deneb’s apparent magnitude, or brightness as seen from Earth, makes it the dimmest of the three bright stars. Its vast distance of possibly 2,600 light years is over 100 times the distance of Vega. If brought as close as Vega, Deneb would be as at least as bright as the quarter moon. It is possibly as bright as 200 thousand Suns; and a huge star, possibly as large in diameter as the orbit of the Earth. For all this it is only 19 or so times the mass of the Sun.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/22/2024 – Saturn’s ring aspect is changing in the next nine months
This is Ephemeris for Thursday, August 22nd. Today the Sun will be up for 13 hours and 41 minutes, setting at 8:36, and it will rise tomorrow at 6:55. The Moon, 3 days past full, will rise at 10:07 this evening.
Saturn graces our evening skies now, but it’s not yet in the evening planet. It will rise tonight at 9:16 PM. However, will set after sunrise, thus still being a morning planet. It will become an evening planet on September 7th, when it reaches opposition from the Sun. It will rise approximately the same time the Sun sets and thereafter will rise before sunset. Saturn’s rings are nearly edge on to us now. Currently, about 2 1/4° from being edge on. They will open up slightly over the next few months to five degrees on November 11th before closing up and becoming edge-on on March 23rd of next year. On that day the rings will disappear for us. However, their presence will only be seen by the thin shadow they cast on the planet.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
The image shows Saturn and its rings on five dates. The first is today, August 22nd 2024. On this date the rings are a little over three degrees from being edge on to us. They will actually open up a bit for nearly three months. On November 11th they will open up to nearly 6°. On March 23rd next year they will be exactly edge on to us and be invisible. The only sign of their presence will be a very thin shadow the rings cast on the planet. The bad part of this is that early next year Saturn will be too close to the Sun to be easily seen from Earth. That includes the Hubble and James Webb space telescopes. It will appear only 10 degrees west of the Sun on that date. It will increase over the next 44 days to 48 degrees on May 6th, when the rings will be edge on to the Sun. In that period the Earth will be looking at the unlit side of the rings. So the rings will be very dim. Only the light filtering through the rings will be seen, and the B ring which is the brightest normally will be just about completely dark due to the density of ring particles in it. After that the rings will open up for the next 7 1/2 years.
Ephemeris: 08/21/2024 – What naked-eye planets are now visible?
This is Ephemeris for Wednesday, August 21st. Today the Sun will be up for 13 hours and 44 minutes, setting at 8:37, and it will rise tomorrow at 6:54. The Moon, 2 days past full, will rise at 9:46 this evening.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Venus might be glimpsed low in the west with Venus lower in the west around 9:15 pm. It will set at 9:31. It is best seen over a very low or lake horizon. Saturn will rise at 9:21 pm, and by 10:30 pm will be low in the east southeast, pretty much by itself. Saturn may look disappointing in telescopes this year since rings are nearly edge on and appear almost as a line through the planet. Jupiter and Mars will be up in the east in the morning, and by 6 am tomorrow, Jupiter will be the brightest starlike object in the sky among the winter stars. Mars will be just below it to the left. Jupiter will rise at 1:06 am, with Mars rising 13 minutes later.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Ephemeris: 08/20/2024 – The Moon will pass Saturn tonight
This is Ephemeris for Tuesday, August 20th. Today the Sun will be up for 13 hours and 47 minutes, setting at 8:39, and it will rise tomorrow at 6:52. The Moon, 1 day past full, will rise at 9:25 this evening.
The bright Moon tonight will have a companion. It will be the planet Saturn, which the Moon will pass below this evening. The Moon being very bright will make it difficult to spot Saturn. So it will seem that Saturn is moving above the Moon, not the other way around. It may take a pair of binoculars to spot Saturn because it will be less than the diameter of the Moon above and to the left of the Moon early in the evening. Moving to the upper right of the Moon towards midnight. Our next full moon will be the Harvest Moon. We’re already seeing the harvest moon effect, that is the Moon rises at nearly the same time on consecutive nights, or almost so. Tomorrow’s Moon will rise only 21 minutes later than tonight’s Moon, at much less than the 50 minutes per night average.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Saturn will be occulted (covered up) by the Moon tonight for portions of the Earth
Ephemeris: 08/19/24 – Dark Energy
This is Ephemeris for Monday, August 19th. Today the Sun will be up for 13 hours and 50 minutes, setting at 8:41, and it will rise tomorrow at 6:51. The Moon, at full today, will rise at 9:02 this evening.
The Big Bang, nearly 14 billion years ago set the universe to be expanding. All the mass of ordinary matter and the dark matter I talked about last week should be slowing that expansion. However, it was discovered, about 20 years ago, that the universal expansion is not slowing down. It is increasing its expansion rate. Astronomers do not really know why. Since expansion requires energy. This new property is called dark energy. It is actually the expansion of space itself. The galaxies are not fleeing by their own motion through space. They are carried by the expanding space around them. It turns out that objects with mass cannot exceed the speed of light, but the expansion of space itself has no speed limit. At least that’s how I understand it.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
Timeline of the universe. A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of “inflation” produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. The afterglow light seen by WMAP was emitted about 375,000 years after inflation and has traversed the universe largely unimpeded since then. The conditions of earlier times are imprinted on this light; it also forms a backlight for later developments of the universe. Public Domain.
Bob Moler's Ephemeris Blog 
