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01/11/2019 – Ephemeris – The bright star in Orion’s knee: Rigel

January 11, 2019 Comments off

Ephemeris for Friday, January 11th. The Sun will rise at 8:18. It’ll be up for 9 hours and 4 minutes, setting at 5:23. The Moon, 3 days before first quarter, will set at 10:55 this evening.

Yesterday I talked about the star Betelgeuse the bright red star in the top left of Orion’s upright rectangle. Orion is seen in the southeast at 9 in the evening. The blue-white star in Orion’s opposite corner is usually brighter. It is Rigel whose longer Arabic name of which Rigel is the first part means “Left Leg of the Giant”. Rigel is a giant itself, actually a super giant star, which is more a measure of its mass than its size, that of 23 solar masses. Its surface temperature is more than twice as hot as the sun. It is 120 thousand times as bright as the sun and 100 times its diameter. Its distance is around 860 light years. Those with telescopes might be able to spot a close companion star to Rigel, just at the edge of the bright arc light image of Rigel itself.

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

Addendum

Orion's brightest stars

Orion’s brightest stars with their names for 9 p.m. January 7, 2019. Click on the image to make Orion a giant hunter. Created using Stellarium..

Rigel A & B

Rigel with its companion star as photographed through a telescope. No attribution. Source: http://washedoutastronomy.com/content/urban-orion?page=1

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01/10/2018 – Ephemeris – Betelgeuse the red giant star in the giant hunter Orion’s shoulder

January 10, 2019 Comments off

Ephemeris for Thursday, January 10th. The Sun will rise at 8:18. It’ll be up for 9 hours and 3 minutes, setting at 5:22. The Moon, 4 days before first quarter, will set at 9:55 this evening.

The bright red star at the upper left corner of the constellation Orion, high in the southeast at 9 p.m. is Betelgeuse. The name is a contraction of an Arabic phrase that means “Armpit of the Central One”. Betelgeuse is a huge star with a diameter four times that of the earth’s orbit of the sun. It is throwing of gas and creating a nebula around itself. It’s distance from us isn’t accurately known, since it doesn’t have a companion star. It’s about 640 light years away, give or take 148 light years or so. Betelgeuse is about 18 times the mass of the sun and 140 thousand times brighter. It is in the latter stages of its short life,of 10 million year so far. Within another million years or so it will probably explode in a supernova.

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

Addendum

Orion's brightest stars

Orion’s brightest stars with their names for 9 p.m. January 7, 2019. Click on the image to make Orion a giant hunter. Created using Stellarium..

Betelgeuse disk

This is the disk of the star Betelgeuse in Orion. It is not an image from an optical telescope of an image created in submillimeter microwaves by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella

Betelgeuse and its nebula. From ESO's Very Large Telescope.

Betelgeuse (inset) and its nebula. From ESO’s Very Large Telescope.

 

01/07/2019 – Ephemeris – The stars of Orion

January 7, 2019 Comments off

Ephemeris for Monday, January 7th. The Sun will rise at 8:19. It’ll be up for 8 hours and 59 minutes, setting at 5:18. The Moon, 2 days past new, will set at 6:57 this evening.

The seven bright stars of Orion now shine in the southeastern sky in the evening. Two shoulder stars, Betelgeuse, and Bellatrix, Two knee stars Saiph, and Rigel, In between are the three belt stars in a row, Alnitak, Alnilam, and Mintaka. Betelgeuse and Rigel are first magnitude stars, among the brightest in the sky, while the others are second magnitude. As far as brightness goes it puts the Big Dipper to shame with its six second magnitude and one third magnitude stars. Of course we in northern Michigan have the Big Dipper always, because it never sets. Orion, only about six months. Due to its position straddling the equator of the sky, Orion is seen by all the people of the world. Parts of him are even seen at the north and south poles.

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

Addendum

Orion's brightest stars

Orion’s brightest stars with their names for 9 p.m. January 7, 2019. Click on the image to make Orion a giant hunter. Created using Stellarium..

 

12/07/2018 – Ephemeris – The Star of Bethlehem: natural event, miracle, or myth? I’ll be following the clues tonight

December 7, 2018 2 comments

Ephemeris for Friday, December 7th. The Sun will rise at 8:06. It’ll be up for 8 hours and 55 minutes, setting at 5:02. The Moon is new today, and won’t be visible.

Tonight at 8 p.m. I will be giving a talk investigating what the Star of Bethlehem may have been. This will be at Northwestern Michigan College’s Rogers Observatory located south of Traverse City on Birmley Road. The talk is a scientific treatment of the matter, rather than a religious one. We’ll look at the usual suspects for what the star was. We’ll see what the Gospel writers may have gotten right and possibly wrong. We’ll look at historical writings and recorded Chinese observations of the heavens around that time. I will be augment this by computer simulations of what might be important celestial events visible around that time. There is no admission charge. There will be viewing of the skies afterward if it’s clear.

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

11/23/2018 – Ephemeris – The Moon and Aldebaran

November 23, 2018 Comments off

Ephemeris for Friday, November 23rd. The Sun will rise at 7:50. It’ll be up for 9 hours and 17 minutes, setting at 5:07. The Moon, at full today, will rise at 5:55 this evening.

Tonight’s full Moon will be accompanied by the bright star Aldebaran, the angry red eye of the constellation Taurus the Bull. Earlier this year we had the last of nearly two years of the Moon every month passing in front of Aldebaran. The tilt of the Moon’s orbit with respect to the Earth’s own orbit of the Sun slides slowly westward with time, so The Moon won’t pass in front of Aldebaran for those of us on Earth again until 2033. This sliding of the Moon’s orbit is called regression of the nodes. A node is where the Moon’s orbital plane crosses the Earth’s. These are places eclipses of the Sun and Moon occur if lined up with the full or new moons. Why regression? The nodal points are moving westward, backward of most motions in the solar system.

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

Addendum

Full moon with Aldebaran
Tonight’s full moon with Aldebaran in the face of Taurus the bull (8 p.m. November 23, 2018). Created using Stellarium.

11/22/2018 – Ephemeris – The little goat star, Capella

November 22, 2018 Comments off

Ephemeris for Thanksgiving Day, Thursday, November 22nd. The Sun will rise at 7:49. It’ll be up for 9 hours and 19 minutes, setting at 5:08. The Moon, 1 day before full, will set at 7:59 tomorrow morning.

Capella is the northernmost first magnitude stars. Tonight it shines in the northeastern sky. First magnitude stars are the 21 brightest stars in the night sky. Capella is the 6th brightest. The name Capella means little goat, though I’ve always known it as the little she goat. Her three Kids are represented by a narrow triangle of stars positioned to the right of her in tonight’s evening sky, though they may be overpowered by the bright Moon tonight. Capella is in the topmost corner of the pentagonal constellation of Auriga the Charioteer. Capella is actually a system of four stars only 43 light years away. And never sets for listeners in the Interlochen Public Radio transmission area, though all bets are off if you’re listening over the Internet from somewhere else.

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

Addendum

Capella with the stars of Auriga and the full Moon
Capella with the stars of Auriga and the full Moon at 8 p.m., November 22, 2018. Created using Stellarium.

10/30/2018 – Ephemeris – Algol the spookiest star in the sky

October 30, 2018 Comments off

Ephemeris for Tuesday, October 30th. The Sun will rise at 8:18. It’ll be up for 10 hours and 16 minutes, setting at 6:34. The Moon, 1 day before last quarter, will rise at 11:53 this evening.

Not all the ghosts and goblins out tomorrow night will be children. One will be out every night because it’s a star. Its name is Algol, from the Arabic for Ghoul Star or Demon Star. The Chinese had a name for it that meant “piled up corpses”. It’s normally the second brightest star in the constellation Perseus the hero, visible in the northeast this evening. The star is located where artists have drawn the severed head of Medusa, whom he had slain. Medusa was so ugly that she turned all who gazed upon her to stone. Algol is her still glittering eye. The star got these names before astronomers found out what was wrong with it. They found out that it does a slow wink every two days, 21 hours.  That’s because Algol is two stars that eclipse each other. Her next evening wink will be dimmest at 8:10 p.m. November 13th.

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

Addendum

Algol Finder
Perseus, Cassiopeia, Andromeda with Algol finder animation for Autumn evenings. Created using Stellarium and GIMP
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Eclipsing Binary Star
Animation of an eclipsing binary star like Algol. Credit: Wikimedia Commons h/t Earth and Sky