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02/15/2021 – Ephemeris – For a few months the Earth had two moons

February 15, 2021 Comments off

This is Ephemeris for President’s Day, Monday, February 15th. Today the Sun will be up for 10 hours and 29 minutes, setting at 6:11, and it will rise tomorrow at 7:41. The Moon, halfway from new to first quarter, will set at 10:22 this evening.

The Moon tonight is a waxing crescent. A four-day-old moon. In binoculars, it shows one complete lunar sea, the Sea of Crises, or if seen on a moon map, Mare Crisium. Speaking of the Moon, for the last few months the Earth had a second moon, with the asteroid designation 2020 SO. This was traveling slowly behind the Earth, and is suspected to be the Centaur upper stage of the Surveyor 2 lunar landing craft launched in 1966. It ended up orbiting the Sun. 2020 SO took a loop and a half around the Earth and is heading back in solar orbit. The ascent stage, Snoopy, from Apollo 10 is also in solar orbit. I hope one day it can be captured on a close approach and brought back to the Earth or the Moon for display. That would be really cool!

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Binocular Moon

The moon as it might appear tonight, at 8 pm, February 15, 2021. Mare Crisium is the round gray sea near the lower right edge. Created using Stellarium.

Animation of object 2020 SO as it encounters the Earth. Also shown is the orbit of the Moon and geostationary satellites. Credit: NASA/JPL – Caltech.

 

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02/08/2021 – Ephemeris – A look at Gemini the twins

February 8, 2021 Comments off

This is Ephemeris for Monday, February 8th. Today the Sun will be up for 10 hours and 9 minutes, setting at 6:01, and it will rise tomorrow at 7:51. The Moon, 3 days before new, will rise at 6:49 tomorrow morning.

Let’s look at another of the winter constellations, and a member of the Zodiac. The constellation of Gemini the Twins is visible high in the southeast, above and left of Orion the hunter at 9 p.m. The namesake stars of the two lads, will be at the left end of Gemini, are nearly overhead and vertically aligned. Castor is on top, while the slightly brighter Pollux is below. From them come two lines of stars that outline the two extending toward Orion. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the sky, so they could be together forever.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Gemini Finder animation

Gemini finder animation for early February at 9 pm (about 3 hours after sunset). Created using Stellarium and GIMP.

02/04/2021 – Ephemeris – Finding Orion’s larger hunting dog

February 4, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, February 4th. Today the Sun will be up for 9 hours and 58 minutes, setting at 5:56, and it will rise tomorrow at 7:56. The Moon, at last quarter today, will rise at 2:19 tomorrow morning.

The great winter constellation or star group Orion the hunter, is located in the southern sky at 9 p.m. His elongated rectangle of a torso is vertical. In the center of the rectangle are three stars in a line that make his belt. As a hunter, especially one of old, he has two hunting dogs. The larger, Canis Major can be found by following the three belt stars of Orion down and to the left. They point to Sirius, the brightest night-time star, also known as the Dog Star. It’s in the heart of a stick figure dog low in the southeast facing Orion that appears to be begging. There’s a fine star cluster, called Messier, or M 41, at the 5 o’clock position from Sirius. It’s easily visible in binoculars or a small telescope.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Orion and his hunting dogs

Orion and his hunting dogs with pointers as seen February. I didn’t have time in the program to mention Canis Minor, the little dog. I expect to cover it in the future, or you can search for Canis Minor in the search box above. Created using Stellarium.

I did not have time to talk about Canis Minor in this program due to the inclusion of M 41. I plan to cover Canis Minor soon. I have in the past. Search for Canis Minor in the search box above.

Star cluster M 41 finder Chart

Star cluster M 41 finder chart. Created using Stellarium.

M 41 up close

M 41 up close. Image courtesy of Tim Hunter and James McGaha, Grasslands Observatory at http://www.3towers.com

 

01/29/2021 – Ephemeris – Let’s get Sirius

January 29, 2021 Comments off

This is Ephemeris for Friday, January 29th. Today the Sun will be up for 9 hours and 42 minutes, setting at 5:47, and it will rise tomorrow at 8:03. The Moon, 1 day past full, will rise at 6:49 this evening.

In the early evening the great constellation of Orion the hunter can be seen in the southeast. Its large rectangle of bright stars is easily visible, even with a full moon. The three stars in a straight line, his belt, tilt downward to the left to a very bright star merrily twinkling lower in the sky. This star is called Sirius, also known as the Dog Star because it’s in the heart of Orion’s larger hunting dog, Canis Major. It is an arc light white star as seen in binoculars or telescope. It is the brightest star in the night sky, and a neighboring star, just twice the distance of the closest star to the Sun at 8.6 light years. It’s name, Sirius, has nothing to do with a dog, but is from the Greek meaning scorching for its brightness or sparkling, due to its intense twinkling.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Sirius finder

A Sirius finder animation for late January/early February at around 8 pm. Even in bright moonlight the seven bright stars of Orion can be seen. The three stars of Orion’s belt make a great pointer to Sirius. Created using Stellarium, GIMP and Libreoffice (for the arrow).

I’ll come back to Sirius several times this winter. Or search for Sirius for other times I’ve talked about this brightest of the night-time stars.

01/28/2021 – Ephemeris – Checking out the full Moon in binoculars

January 28, 2021 1 comment

This is Bob Moler with Ephemeris for Thursday, January 28th. Today the Sun will be up for 9 hours and 40 minutes, setting at 5:46, and it will rise tomorrow at 8:04. The Moon, at full today, will rise at 5:37 this evening.

The winter full moon rises very high in the sky. It follows a path across the sky at night that the Sun will take six months from now in July. On the full moon with binoculars or small telescope most craters are not very visible due to the lack of shadows. There are exceptions, those with dark or bright floors. The lunar seas are the large dark areas. These positions are for the early evening, as the Moon rises. Grimaldi can be seen as a dark ellipse near the lower left edge. Plato another dark ellipse is in the upper left. A bright spot with a darker circle around it on the lower right is the crater Tycho, which has several rays of ejecta laid out over long distances across the face of the Moon. Finally, there’s a bright spot on the left side of the Moon. That is the crater Aristarchus.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Annotated full Moon

Annotated full Moon. Major seas in upper case. Prominent craters in lower case. See text below. The image is rotated for 8 pm in late January. Credit Bob Moler.

Lunar seas

A – Mare Crisium (Sea of Crises)
B – Mare Fecunditatus (Sea of Fertility)
C – Mare Tranquillitatis (Sea of Tranquility)
D – Mare Serenitatis (Sea of Serenity)
E – Mare Imbrium (Sea of Showers)
F – Oceanus Procellarum (Ocean of Storms)
G – Mare Nubium (Sea of Clouds)
H – Mare Humorum (Sea of Moisture)
I – Mare Nectaris (Sea of Nectar)

Craters

a – Grimaldi
b – Plato
c – Tycho
d – Aristarchus
e – Copernicus (Not mentioned in the program due to time constraints)

01/25/2021 – Ephemeris – Why is the sky with the full moon gray?

January 25, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, January 25th. Today the Sun will be up for 9 hours and 33 minutes, setting at 5:42, and it will rise tomorrow at 8:07. The Moon, 3 days before full, will set at 6:46 tomorrow morning.

The bright Moon is dominating the night sky now. Only the brighter stars are visible, with the fainter stars and constellations overwhelmed by the bright moonlit sky. It seems odd, but the gray clear moonlit sky that we see with our eyes is as blue as the daytime sky. Only it’s too dim to register on the cones in our retinas that can see color. The rods in our retinas can pick up light much better, especially if it is in the green part of the spectrum. We are pretty much insensitive to red at low light levels and color-blind as well. Star color is also subtle, and can be seen only in brighter stars. The colors run, from the hottest stars to the coolest: blue, white, yellow, orange and red. Also, there is a color shift at night. Stars with the same temperature as the Sun appear yellowish.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

 

01/22/2021 – Ephemeris – Mercury will be at it’s greatest angular distance from the Sun in the evening tomorrow

January 22, 2021 Comments off

This is Ephemeris for Friday, January 22nd. Today the Sun will be up for 9 hours and 26 minutes, setting at 5:37, and it will rise tomorrow at 8:10. The Moon, 2 days past first quarter, will set at 3:43 tomorrow morning.

The planet Mercury, tomorrow night, will reach its greatest elongation or separation east of the Sun. It will be visible low in the southwestern sky around and for a half hour or so after 6 pm. Mercury, being the closest planet to the Sun, never strays far from it. Here in the Northern Hemisphere never see it outside of twilight. It’s apparent angular separation from the Sun will be 18.6 degrees. We will have a somewhat better view of an evening appearance of Mercury in May when Venus will again be in our evening sky and near Mercury. Mercury takes 88 days on to orbit the Sun. However, we are viewing it from another moving planet. So it takes about 116 days for Mercury to appear to orbit the Sun from our vantage point.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Mercury at greatest elongation at sunset January 23, 2021. It also shows Mercury’s orbit that evening plus Jupiter. Saturn is actually behind the Sun that evening as can be seen by the over display of the labels for Saturn and the Sun. Created using Stellarium by removing Earth’s atmosphere.

01/15/2021 – Ephemeris – The constellation Lepus the hare

January 15, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, January 15th. Today the Sun will be up for 9 hours and 12 minutes, setting at 5:28, and it will rise tomorrow at 8:15. The Moon, 2 days past new, will set at 8:17 this evening.

Orion, the central winter constellation is seen in the southern sky this evening. He is a hunter, as artists depict him, he is preoccupied with the charge of Taurus the bull from the upper right. At Orion’s feet, and unnoticed by him is the small constellation of Lepus the hare. It’s very hard to see a rabbit in its eight dim stars: however, I can see a rabbit’s head ears and shoulders. A misshapen box is the head and face of this critter facing to the left. His ears extend upwards from the upper right star of the box, and the bend forward a bit. Two stars to the right of the box and a bit farther apart hint at the front part of the body. In Lepus telescopes can find M79, a distant globular star cluster, one of the few visible 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

My view of Lepus the hare.

My view of Lepus the hare. Star field from Cartes du Ciel. Desert Cottontail drawing from Arizona-Senora Desert Museum website. Superimposed with GIMP.

Lepus

An animation showing the stars, constellations and artwork of Lepus, Orion and Taurus from Stellarium. The constellation lines suggest a rabbit ears TV antenna. Created using Stellarium and GIMP.

01/12/2021 – Ephemeris – The celestial river Eridanus

January 12, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, January 12th. Today the Sun will be up for 9 hours and 7 minutes, setting at 5:25, and it will rise tomorrow at 8:17. The Moon, 1 day before new, will rise at 8:58 tomorrow morning.

One of the more obscure constellations around is Eridanus, which depicts a river. The river starts near the lower right corner of Orion, near the bright star Rigel and flows to the right then down near the southwestern horizon, then it meanders along the horizon to the south before turning below the horizon. One has to travel to the far south to see the southern terminus of the river, the bright star Achernar. Writers over the ages have seen here the Nile and the Earth circling river Ocean of the flat earth days. Achernar is actually two stars, the brightest was discovered to be the flattest star known, due to its rapid spin. The dimensions of Achernar A has been determined to be twice as wide across its equator than from pole to pole. It’s 139 light years away.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Eridanus

An animation of the constellation Eridanus which is a river that flows from Rigel in Orion to the star Achernar below our southern horizon at latitude 45 degrees north. Create using Stellarium and GIMP.

01/11/2021 – Ephemeris – Procyon, the before the Dog Star

January 11, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, January 11th. Today the Sun will be up for 9 hours and 5 minutes, setting at 5:23 pm, and it will rise tomorrow at 8:17 am. The Moon, 2 days before new, will rise at 8:05 tomorrow morning.

Visible low in the east at 8 p.m. appears the star Procyon. To its right and below is Sirius the brightest night-time star. Procyon is the bright star in the constellation Canis Minor, or lesser dog. I can find only one other star in Canis Minor. Perhaps it’s a hot dog. If Sirius, in Canis major is the Dog Star then Procyon should be the Little Dog Star. However, Procyon is an interesting name. It means “Before the dog”, which is an allusion to the fact that Procyon, though east of Sirius actually rises before it. This is due to Procyon’s more northerly position. This effect doesn’t work south of the equator, however. Sirius will rise at about 7:30 tonight. Procyon is a star much like Sirius but is 32% farther away. It’s 11.4 to Sirius’ 8.6 light years away.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Orion and his hunting dogs in early winter

Orion and his hunting dogs in early winter (8 pm, January 11, 2021) showing that Procyon does rise before Sirius.