Archive
09/26/2014 – Ephemeris – Mars meets its rival
Ephemeris for Friday, September 26th. The sun will rise at 7:34. It’ll be up for 11 hours and 58 minutes, setting at 7:32. The moon, 2 days past new, will set at 8:45 this evening.
The planet Mars and the bright star Antares will appear at their closest tomorrow night. The name of the star Antares means “Rival of Mars”. “Ant” meaning anti, “Ares”, the Greek equivalent to the Roman god Mars. This is about a 26 month recurrence, give or take. Usually Mars is way brighter than Antares, or way dimmer. This time Mars and Antares are the same brightness. Both planet and star have the same color, kind of a faded orange color, made redder by being low in our sky which drains even more of the blue out. The reason Mars is red is that its surface is rusty. Antares is another matter. It is a cool red giant star. Well, cool on the outside by hotter than the sun’s interior on the inside where it’s changing helium into carbon and oxygen for power. Hint: Mars is always on top. Also tomorrow night the crescent Moon will be just to the right of Saturn.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Mars appears its closest to Antares. Here seen low in the southwest at 8:30 p.m. on September 27, 2014. The Moon, near Saturn is too small to show a phase. Created using Stellarium.
Saturn with the crescent moon. Earthshine may still be visible on the three day old Moon’s night side. Created using Stellarium.
Acme Fall Festival
The Grand Traverse Astronomical Society will be at the Acme Fall Festival at Flintfields Horse Park on Bates Rd, North of M72, which runs from 10 a.m. to 4 p.m. Saturday the 27th. The society will bring telescopes, including the 25 inch Dobsonian telescope and the Solar Telescope to view the Sun in white light and the light of the element hydrogen. There will also be exhibits and free stuff from NASA for the kids.
09/25/2014 – Ephemeris – Capella rising
Ephemeris for Thursday, September 25th. The sun will rise at 7:33. It’ll be up for 12 hours and 1 minute, setting at 7:34. The moon, 1 day past new, will set at 8:13 this evening.
A bright star called Capella has slowly been rising in the northeastern sky in the evenings for the past few months. At 9 p.m. now it is low in the north-northeast far below the letter “W” shaped constellation of Cassiopeia. This winter Capella will be overhead the highest of winter’s seven brilliant first magnitude stars. Capella never quite sets for anyone north of Ludington. It is what is called a circumpolar star. Due to its brightness, and being the closest first magnitude star to the north pole, Capella appears to move slowly as the earth rotates, and spends summer and autumn evenings close to the horizon, and has in years past elicited a few phone calls and other queries about that ‘bright object in the northeast’. When it’s higher the rest of its constellation Auriga the Charioteer will be visible.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Capella cruising up from the north (thanks to the Earth’s rotation) on September 25 at 9 p.m. Created using Stellarium.
07/24/2014 – Ephemeris – A look at Altair the third star of the Summer Triangle
Ephemeris for Thursday, July 24th. The sun rises at 6:20. It’ll be up for 14 hours and 56 minutes, setting at 9:17. The moon, 2 days before new, will rise at 5:21 tomorrow morning.
The Summer Triangle Is high in the east to southeast sky in the evening. The southernmost star of the Summer Triangle is Altair, in the southeast. Altair is the closest of the three stars at a distance of 16.7 light years away. One light year is nearly 6 trillion miles, that’s 6 followed by 12 zeros. Altair is nearly 11 times the brightness of the sun. If seen at Altair’s distance, the sun would only be as bright as one of the two stars that flank it in our sky. What is rather different about Altair is its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in only 9 hours, and would show a decidedly squashed appearance if seen close up. Our sun’s a slow poke, taking nearly a month to rotate just once.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Deneb with the other stars and constellations in the Summer Triangle. Created using Stellarium.
False-color image of the rapidly rotating star Altair, made with the MIRC imager on the CHARA array on Mt. Wilson. Credit: Ming Zhao, University of Michigan
07/18/2014 – Ephemeris – Deneb is the brightest star of the Summer Triangle… Really
Ephemeris for Friday, July 18th. Today the sun will be up for 15 hours and 8 minutes, setting at 9:22. The moon, at last quarter today, will rise at 12:58 tomorrow morning. Tomorrow the sun will rise at 6:15.
At 11 this evening the bright star Deneb in Cygnus the swan will be moderately high in the east northeast. Deneb is the dimmest star of the summer triangle. Of the other stars of the triangle, Vega is nearly overhead, and Altair to the southeast. While Deneb’s apparent magnitude, or brightness as seen from Earth, makes it the dimmest of the three bright stars, Deneb has a vast distance of possibly 1,550 light years. If brought as close as Vega, Deneb would be several times brighter than Venus. For all this it is only 13-20 times the mass of the sun. It will have an extremely short life and will explode, go supernova, in perhaps a few million years. Closer to home, check out the Sun at Kingsley Heritage Days This Saturday and Sunday.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Deneb and the Northern Cross section of Cygnus the swan. Created using Stellarium.
One of my old photographs of Deneb and the North American Nebula digitized from a slide.
The North American Nebula, visible as a faint smudge in binoculars or the naked eye may be ionized and illuminated by Deneb. It’s distance appears to be comparable to that of Deneb.
You may note that previous postings about Deneb over the years have given different distances of Deneb. That just denotes how difficult it is to pin down its distance.
07/04/2014 – Ephemeris – Find patriotic red, white and blue stars
Ephemeris for Independence Day, Friday, July 4th. Today the sun will be up for 15 hours and 27 minutes, setting at 9:30. The moon, 1 day before first quarter, will set at 1:03 tomorrow morning. Tomorrow the sun will rise at 6:03.
On this patriotic day let’s look for some red, white, and blue stars. Red is easy, the red star Antares is seen in the south at 11 p.m. Mars, the red planet, in the southwest, can be added even though it’s not technically a star. White is easy too, the official white calibration star Vega high in the east at 11 p.m. The blue star is really blue-white. The brightest of these out at 11 p.m. is Spica, low in the southwest. The color is best seen in binoculars. Star colors are quite subtle, and are an indicator of the temperature of their outer gaseous layers. The temperature of a stars outer layers, in order of their increasing temperatures, red, white and blue, is not related to the temperature in their cores. Of these three the coolest on the outside, Antares is really the hottest inside, using helium as fuel.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Red white and blue stars for Independence Day at 11 p.m. on July 4, 2014. Created using Stellarium.
06/24/2014 – Ephemeris – The bright star Vega is high in the east
Ephemeris for Tuesday, June 24th. Today the sun will be up for 15 hours and 33 minutes, setting at 9:31. The moon, 3 days before new, will rise at 4:53 tomorrow morning. Tomorrow the sun will rise at 5:58.
The bright star high in the east is Vega, one of the stars of the Summer Triangle an informal constellation called an asterism. Vega belongs to the official constellation Lyra the harp, which includes a narrow parallelogram of stars to its south. Vega is regarded by astronomers as a standard calibration star. Though a first magnitude star, its actual magnitude is 0.03. It is a type A0 pure white star, and is 27 light years away. Astronomers however got a shock in 1983 when calibrating the Infrared Astronomy Satellite (IRAS) on it: Vega showed an excess of Infrared radiation that means the star is orbited by a disk of dust, perhaps the beginnings of a planetary system. Due to the slow wobble of the earth’s axis Vega will be our pole star in 14 thousand years.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle. Created using Stellarium and The Gimp.
Vega in the mid-infrared from the Spitzer Space Telescope. Credit: NASA/JPL-Caltech/University of Arizona
02/20/2014 – Ephemeris – Winter Circle plus 1
Ephemeris for Thursday, February 20th. The sun will rise at 7:34. It’ll be up for 10 hours and 43 minutes, setting at 6:18. The moon, 2 days before last quarter, will rise at 12:27 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. Six of these stars lie in a large circle centered on the seventh. This circle is up at 9 p.m. Starting high overhead is Capella in Auriga the charioteer. Moving down clockwise is Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find Rigel. Down and left is the brightest star of all Sirius the Dog Star in Canis Major, lowest of these stars in the south-southeast. Moving up and left is Procyon in Canis Minor, Above Procyon is Pollux in Gemini the twins. All these are centered on Betelgeuse the bright red star in Orion’s shoulder. The interloper this year is Jupiter which is situated in Gemini and outshines them all.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Winter Circle plus Jupiter at 9 p.m. on February 20, 2014. Created using Stellarium.
12/27/2013 – Ephemeris – The star Procyon: “Before the Dog”
Ephemeris for Friday, December 27th. The sun will rise at 8:18. It’ll be up for 8 hours and 50 minutes, setting at 5:08. The moon, 2 days past last quarter, will rise at 3:48 tomorrow morning.
Yesterday I talked about the brilliant star Sirius, the dog star pointed to by the stars of the belt of Orion. Today we’ll look at another dog star. Procyon, the bright star in Canis Minor, the lesser dog. It is pointed to by the top two stars in the Orion rectangle Bellatrix and Betelgeuse. One of the translations of Procyon means “Before the Dog”. This seemingly odd title is explained that even though Procyon is east of Sirius and all things being equal, well at least latitude or declination the eastern star should rise after the western star. However Procyon is north of Sirius and if one is sufficiently north of the equator, the eastern most star can rise first. This is what happens. Procyon is a bit farther away than Sirius and isn’t quite as bright either.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Procyon is already up as Sirius rises. Procyon also sets after Sirius. Created using Stellarium.
Note: Stellarium approximates atmospheric extinction, that is dims objects when they are near the horizon an effect due to looking through more of the Earth’s atmosphere when looking close to the horizon. That’s why Sirius looks rather fainter than in yesterday’s image.
12/26/2013 – Ephemeris – Sirius, the brightest night-time star
Ephemeris for Thursday, December 26th. The sun will rise at 8:18. It’ll be up for 8 hours and 49 minutes, setting at 5:08. The moon, 1 day past last quarter, will rise at 2:40 tomorrow morning.
At 9 in the evening the great constellation of Orion the hunter can be seen in the southeast. Its large rectangle of bright stars is tilting to the left, while in the center is a row of three stars, his belt. These stars tilt downward and a bit to the left to a very bright star merrily twinkling above the horizon in the southeast. This star is called Sirius, also known as the Dog Star because it’s in the heart of Orion larger hunting dog, Canis Major. It is an arc light white star as seen in binoculars or telescope. It’s 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.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
How to find Sirius from Orion. 9 p.m., December 26, 2013. Created using Stellarium.
12/16/2013 – Ephemeris – Orion’s bright blue-white star Rigel
Ephemeris for Monday, December 16th. The sun will rise at 8:13. It’ll be up for 8 hours and 49 minutes, setting at 5:03. The moon, 1 day before full, will set at 8:07 tomorrow morning.
Last week I talked about the star Betelgeuse the bright red star in the top left of Orion’s rectangle in the hunter’s shoulder. 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 17 solar masses. Its surface temperature is more than twice as hot as the sun. It is 130 thousand times as bright as the sun and 74 times its diameter. Its distance is around 860 light years. A telescope might reveal a close companion star to Rigel, off the edge of the bright arc light image of Rigel itself.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Taurus and Orion with Orion’s brightest stars named. Created using Stellarium.
Bob Moler's Ephemeris Blog 