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12/17/2020 – Ephemeris – Betelgeuse, Betelgeuse… Nope not saying it again

December 17, 2020 Comments off

This is Bob Moler with Ephemeris for Thursday, December 17th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:03, and it will rise tomorrow at 8:15. The Moon, 3 days past new, will set at 8:18 this evening.

The constellation Orion the hunter will have completely risen by 8 pm this evening. The leftmost bright red star in his shoulder is Betelgeuse. It’s phonetically spelled name (Beetle Juice) made the title of a movie in 1988. A year ago it’s dramatic dimming for a while caused some to wonder that it was about to explode in a supernova. Betelgeuse does normally vary a bit in brightness, but that was the most ever recorded. It’s a red giant star with a mass of 16 to 19 times the Sun’s. Its distance is thought to be about 550 light years away. It is difficult to measure the distance of single bright stars, even with satellites. Its age is maybe 8 to 8 ½ million years old out of a life expectancy of 10 million years, compared to the Sun’s 10 billion year life expectancy.

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

Addendum

Orion

Orion at 8 pm or about 3 hours after sunset in mid December. Its seven brightest stars make an unmistakable pattern with only Betelgeuse and Rigel labeled. Created using Stellarium.

Betelgeuse before and after dimming

This comparison image shows the star Betelgeuse before and after its unprecedented dimming. The observations, taken with the SPHERE instrument on ESO’s Very Large Telescope in January and December 2019, show how much the star has faded and how its apparent shape has changed. Credit: ESO/M. Montargès et al.

Betelgeuse's dust plume

An image of the star Betelgeuse taken in infrared shows it’s surrounded by a vast cloud of dust that erupted from the surface (the bright star itself is masked out, though an image of it has been superposed there for scale — the star is about the size of the orbit of Jupiter, over a billion km wide). Credit: ESO/P. Kervella/M. Montargès et al., Acknowledgement: Eric Pantin via Phil Plait’s Bad Astronomy blog on syfy.com.

Categories: Ephemeris Program, Stars Tags: ,

12/16/2020 – Ephemeris – Let’s look for the naked-eye planets for this week

December 17, 2020 Comments off

This is Bob Moler with Ephemeris for Wednesday, December 16th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:03, and it will rise tomorrow at 8:14. The Moon, 2 days past new, will set at 7:09 this evening.

Let’s look for the naked-eye planets for this week. Jupiter and Saturn are both low in the southwestern sky from 6 to 7 pm. Jupiter is the very bright one. Above and left it by half a degree or one moon width will be dimmer Saturn. Below them tonight will be the thin crescent Moon. They will cross paths for us on the evening of December 21st and be seen in the same low power telescope field that evening. Jupiter will set first tonight at 7:40 pm with Saturn following four minutes later. Quite high in the southeast at that hour will be Mars, still in Pisces. Mars’ distance is increasing to 71 million miles (114 million kilometers) away. It will set at 2:55 tomorrow morning. Brilliant Venus will rise at 6:16 am in the east-southeast as it seems to retreat slowly toward the Sun, but actually it’s heading way around behind the Sun.

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

Addendum

Jupiter and Saturn with Moon @ 6 pm

Jupiter and Saturn with Moon at 6 pm tonight December 16, 2020. Created using Stellarium.

Evening planet panorama

Evening planet panorama showing Mars, Jupiter, Saturn and the Moon setting at 6:30 pm December 16, 2020. Click on the image to enlarge. Created using Stellarium.

Venus in the morning

Venus low in the southeast at 7 am December17, 2020. Venus is all by its lonesome in the morning sky. No need for a panorama, so we’re zoomed in a  bit. The morning sky has is not as friendly to morning planets as it was earlier in autumn season as we embark into winter next week. Created using Stellarium.

Telescopic planets

The planets as seen in a telescope (north up) with the same magnification for the night of December 16/17, 2020. Times of the display are: Jupiter and Saturn, 6 pm and Mars, 8 pm; Venus, 7 am. Apparent diameters: Jupiter, 33.49″; Saturn, 15.41″, rings, 35.90″; Mars, 12.20″, and Venus, 11.10″. Europa is transiting Jupiter and will be generally invisible. Mars also displays an enlargement showing surface detail. Mars was closest to the Earth this go-a-round on October 6. The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on December 16, 2020. The night ends on the left with sunrise on the 17th. I’m afraid that the labels for Jupiter and Saturn will overlap, since the planets are getting very close. Click on the image to enlarge. Created using my LookingUp program.