04/21/2021 – Ephemeris – Let’s search for the naked-eye planets for this week
This is Ephemeris for Wednesday, April 21st. Today the Sun will be up for 13 hours and 47 minutes, setting at 8:35, and it will rise tomorrow at 6:46. The Moon, 1 day past first quarter, will set at 4:56 tomorrow morning.
Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find in the evening is Mars. It can be found in the west at 10 pm tonight, between the constellations of Taurus the bull below and Gemini the twins above. Tonight it’s just off Castor’s big toe. Mars will set at 1:30 am. Venus is now just east of the Sun, setting 31 minutes after sunset. It will be late May or early June before it will be easily spotted in the evening twilight. Mercury is between the Sun and Venus. Saturn and Jupiter are at a far enough angle from the Sun to be spotted in the morning twilight. Saturn will rise at 3:51 am, with Jupiter rising at 4:28 am. By 6 am they will be low in the southeast.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/20/2021 – Ephemeris – SpaceX gets NASA contract for Human Landing System for the Artemis (Moon) Program
This is Bob Moler with Ephemeris for Tuesday, April 20th. Today the Sun will be up for 13 hours and 44 minutes, setting at 8:34, and it will rise tomorrow at 6:47. The Moon, at first quarter today, will set at 4:24 tomorrow morning.
Late last week NASA announced that it had selected SpaceX to provide the Human Lander System for the Artemis program. That lander is the lunar variant of the Starship SpaceX is currently testing near Boca Chica, Texas, just north of the mouth of the Rio Grande. A Starship consists of two stages: a booster called Super Heavy and the Starship upper stage. The Super Heavy returns to the launch site, while the Starship must be refueled several times in orbit to be able to head on out to the Moon. The astronauts would be launched as planned in an Orion capsule with the Space Launch System, then transfer the astronauts to the Starship waiting in lunar orbit or from the Lunar Gateway also in lunar orbit for the trip down to the lunar surface.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
NASA’s Source Selection Document (the rationale for their selection): https://www.nasa.gov/sites/default/files/atoms/files/option-a-source-selection-statement-final.pdf
04/19/2021 – Ephemeris – The Moon tonight, Yutu the Jade Rabbit
This is Ephemeris for Monday, April 19th. Today the Sun will be up for 13 hours and 42 minutes, setting at 8:33, and it will rise tomorrow at 6:49. The Moon, 1 day before first quarter, will set at 3:47 tomorrow morning.
Let’s take a look at the Moon tonight. Binoculars or a small telescope will be handy for seeing the lunar features. The Moon will be at actual first quarter at 3 am tomorrow morning so the terminator or in this case sunrise line on the Moon will cut it nearly in half. To the naked eye the face of the Man in the Moon isn’t yet noticeable, but the top part of the upside down Chinese rabbit Yutu can be glimpsed. His ears are the seas of Fertility and Nectar, his head is the Sea of Tranquility, and the top part of his body is the Sea of Serenity. The lower part of his body and his arms pulverizing medicine with a mortar and pestle will have to wait until the Moon is nearer full. Yutu is the pet rabbit of the Chinese Moon goddess Chang’e.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/16/2021 – Ephemeris – Virtual Star Party for the Sleeping Bear Dunes tonight
This is Bob Moler with Ephemeris for Friday, 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, 4 days before first quarter, will set at 1:15 tomorrow morning.
Tonight the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society will hold an online star party this evening starting around 9 pm via the Zoom app available for Android smartphones, iPhones and computers. Instructions for joining are on the society’s website http://www.gtastro.org or the Sleeping Bear Dunes National Lakeshore 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 crescent Moon. Then we move out beyond the solar system into our galaxy for star clusters and beyond our galaxy into the distant galaxies of spring skies.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
We will be looking also at a few star clusters and out the thin side of our Milky Way Galaxy to lots of other galaxies.
04/15/2021 – Ephemeris – The Moon tonight – libration
This is Bob Moler with Ephemeris for Thursday, April 15th. Today the Sun will be up for 13 hours and 30 minutes, setting at 8:28, and it will rise tomorrow at 6:56. The Moon, 4 days past new, will set at 12:14 tomorrow morning.
The crescent Moon tonight is in the constellation of Taurus the bull. The bright star Aldebaran will be just to the left of the Moon. In binoculars the dark oval spot visible on the Moon is the Sea of Crises or Mare Crisium a small dark lava plain. The Moon’s rotation is quite uniform, however its orbit isn’t circular, so the Moon’s appearance seems to rock a bit back and forth over the month. It’s an effect called libration. And one way to track that is to note how close the Sea of Crises is to the edge of the Moon. A week from now that sea will appear its closest to the edge. Astronomers call the edge of the Moon the limb. The phase line between day and night on the Moon is called the terminator. Now as the Moon is waxing, it is the morning or sunrise terminator.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/14/2021 – Ephemeris – Let’s search for the naked-eye planets for this week
This is Bob Moler with Ephemeris for Wednesday, April 14th. Today the Sun will be up for 13 hours and 27 minutes, setting at 8:27, and it will rise tomorrow at 6:58. The Moon, 3 days past new, will set at 11:11 this evening.
Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find in the evening is Mars. It can be found in the west at 10 pm tonight, between the constellations of Taurus the bull below and Gemini the twins above. Mars will set at 1:39 am. Venus is now just east of the Sun, setting 23 minutes after sunset. It will be late May or early June before it will be easily spotted in the evening twilight. The other three naked-eye planets are west of the Sun in the morning sky. Only Saturn and Jupiter are at a far enough angle from the Sun to be spotted in the morning twilight. Saturn will rise at 4:17 am, with Jupiter rising at 4:53 am. By 6 am they will be low in the southeast.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/13/2021 – Ephemeris – Hydra slithers across the southern sky
This is Bob Moler with Ephemeris for Tuesday, April 13th. Today the Sun will be up for 13 hours and 24 minutes, setting at 8:25, and it will rise tomorrow at 6:59. The Moon, 2 days past new, will set at 10:08 this evening.
In the southern evening sky can be found the constellation of Hydra the water snake. Unlike the monster of the same name this Hydra has but one head, which is its most distinctive part. At 10 p.m. look midway up the sky in the south-southwest. The head of Hydra is located below a line from the constellation Leo the Lion in the south and Gemini high in the west-southwest. Its head is directly below Cancer the crab in the southwest. Hydra’s head is a small but distinctive group of 6 stars that make a loop and the snake’s slightly drooping head. The rest of Hydra wends its way to the southeastern horizon, and eventually ends near the late spring constellation of Libra the scales. Over the next few hours Hydra will be seen slithering across the southern sky.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/12/2021 – Ephemeris – Human space flight began 60 years ago today
This is Bob Moler with Ephemeris for Monday, April 12th. Today the Sun will be up for 13 hours and 21 minutes, setting at 8:24, and it will rise tomorrow at 7:01. The Moon, 1 day past new, will set at 9:05 this evening.
60 years ago today Yuri Gagarin a Soviet Air Force pilot became the first cosmonaut and first person to orbit the Earth in his Vostok-1 spacecraft. The event has been celebrated around the world since 2001 as Yuri’s Night. Gagarin was strictly a passenger on his flight, but was given a key to override the automated functions of the spacecraft to take over manually if needed. He ejected from the capsule as planned to land by parachute. His flight came three weeks before the United States and NASA launched Alan Shepard on his sub-orbital flight in his Freedom 7 Mercury Capsule on May 5th 1961. It wasn’t until February 20th the next year that John Glenn made three orbits of the Earth in his Friendship 7 Capsule to match Gagarin’s feat.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/09/2021 – Ephemeris – Follow the arc to Arcturus
This is Bob Moler with Ephemeris for Friday, April 9th. Today the Sun will be up for 13 hours and 12 minutes, setting at 8:20, and it will rise tomorrow at 7:06. The Moon, 2 days before new, will rise at 6:57 tomorrow morning.
The fourth or fifth brightest night-time star, depending on whose list you see, is now up in the east in the evening. It is Arcturus, a bright star with an orange hue. It can be found otherwise by finding the Big Dipper and tracing out and extending the curve of the handle and “Follow the arc of the handle to Arcturus”, to remember the name of the star and how to find it. Arcturus is about 37 light years from us and is moving quite rapidly across the sky, compared to most stars, though one would not notice it to the naked eye in one’s lifetime. Arcturus is slightly more massive than our Sun, and about 7 billion years old, and is entering its red giant stage of life after using all the hydrogen fuel in its core. Our Sun, being slightly less massive will survive on hydrogen a bit longer.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
I’ll be talking more about Arcturus and the constellation it’s in Boötes the herdsman, a kite shaped constellation that’s currently laying on its side. He’s not herding, but chasing the Great Bear. But that’s another story.
04/08/2021 – Ephemeris – Ursa Major, the Great Bear
This is Bob Moler with Ephemeris for Thursday, 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, 3 days before new, will rise at 6:37 tomorrow morning. | 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 pm 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 Anishinaabe 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. However, the weasel-like Fisher fits the stars completely.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Bob Moler's Ephemeris Blog 