Archive
06/09/2016 – Ephemeris – Waiting for the first stars to appear
Ephemeris for Thursday, June 9th. Today the Sun will be up for 15 hours and 30 minutes, setting at 9:27, and it will rise tomorrow at 5:56. The Moon, 3 days before first quarter, will set at 12:59 tomorrow morning.
Lets look at the first stars and planets to appear tonight as it gets dark. The first object to appear will be the fat crescent Moon in the southwest. The planet Jupiter will be the next to appear after sunset left and above the Moon. Mars, low in the southeast will appear reddish, shortly thereafter. Looking very high in the southeast, the fourth brightest nighttime star will appear. This will be Arcturus with an orange hue. Saturn should appear to the left and below Mars. Soon other stars will appear including the Big Dipper overhead. Other bright stars will appear, the summer star Vega low in the northeast. Regulus between Jupiter and the Moon and Spica between Jupiter and Mars.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The sky at about 10 p.m. or a little later, watching the first stars and planets appear. Created using Stellarium. If viewing using Firefox right-click on the image and select View Image to enlarge.
11/20/2015 – Ephemeris – Finding the bright stars of November
Ephemeris for Friday, November 20th. The Sun will rise at 7:46. It’ll be up for 9 hours and 24 minutes, setting at 5:10. The Moon, 1 day past first quarter, will set at 2:17 tomorrow morning.
The Moon is beginning to brighten up the sky making constellation spotting somewhat difficult, so I thought we’d look for the brightest stars. High in the west are the three stars of the Summer Triangle. At the bottom in the southwest is Altair, the first of these to set. A bit north of west the brightest, Vega. Highest in the west is Deneb, which won’t officially set for those Interlochen northward. Low in the south is the loneliest star Fomalhaut. In the northeast is the winter star Capella, which also doesn’t set for the IPR listener area, but spends summer nights hiding behind hills and trees in the north. Low in the east is the last of our bright stars, Aldebaran in Taurus the bull, which will be playing hide and seek with the Moon next week.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The bright first magnitude stars of autumn shown for 8 p.m. November 20, 2015. If you are closer to your time meridian, we’re 43 minutes behind ours, you will see two more bright stars in the east: Red Betelgeuse and blue-white Rigel. Created using Stellarium.
07/27/2015 – Ephemeris – Deneb, the dimmest of the Summer Triangle stars. But is it really?
Ephemeris for Monday, July 27th. The Sun rises at 6:23. It’ll be up for 14 hours and 51 minutes, setting at 9:14. The Moon, 3 days past first quarter, will set at 3:36 tomorrow morning.
This evening when it gets dark the bright star Deneb in Cygnus the swan will be high in the east northeast. Deneb is the dimmest star of the summer triangle. Of the other stars of the triangle, Vega is very high in the east, while Altair is lower in the southeast. While Deneb’s apparent magnitude, or brightness as seen from earth, makes it the dimmest of the three bright stars, Deneb’s vast distance of possibly 2,600 light years makes it over 100 times the distance of Vega. If brought as close as Vega, Deneb would be almost as bright as the full moon. It is as bright as two hundred thousand suns. It apparently has run out of hydrogen in its core. Once a blue super giant star, it’s currently evolving through the white supergiant stage.
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.
One of my old photographs of Deneb and the North American Nebula digitized from a slide.
The Hertzsprung-Russell diagram of star luminosity vs. surface temperature. Note that Deneb is at the top center, while the Sun is lower on the main sequence. Credit: European Southern Observatory (ESO).
07/21/2015 – Ephemeris – Vega, the brightest star of the Summer Triangle
Ephemeris for Tuesday, July 21st. Today the Sun will be up for 15 hours and 3 minutes, setting at 9:20. The Moon, 3 days before first quarter, will set at 12:01 tomorrow morning. Tomorrow the Sun will rise at 6:17.
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 was regarded by astronomers as a standard calibration star. Though a first magnitude star, its actual magnitude is 0.03 and slightly variable. It is a type A0 (A-zero) pure white star, and is 25 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.
Magnified view of Lyra. Created using Stellarium.
Vega in the mid-infrared from the Spitzer Infrared Satellite. Credit: NASA/JPL-Caltech/University of Arizona
07/17/2015 – Ephemeris – The constellation of the harp now and Venus and the Moon tomorrow night.
Ephemeris for Friday, July 17th. Today the Sun will be up for 15 hours and 11 minutes, setting at 9:24. The Moon, 2 days past new, will set at 10:07 this evening, and tomorrow the Sun will rise at 6:14.
High in the east at 11 p.m. can be found a bright star just above a small, narrow, but very distinctive parallelogram of stars. They are the stars of the constellation Lyra the harp. The bright star is Vega, one of the twenty one brightest stars, called first magnitude stars. Vega is actually the 5th brightest night time star. The harp, according to Greek mythology, was invented by the god Hermes. The form of the harp in the sky, is as he had invented it: by stretching strings across a tortoise-shell. Hermes gave it to his half-brother Apollo, who in turn gave it to the great musician Orpheus.
Looking westward tomorrow night the planet Venus will appear about 2 moon widths above the crescent Moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Lyra as a tortoise-shell harp. Created using Stellarium and free clip art.
Venus appears above the thin crescent moon with Jupiter to the right at 10 p.m. Saturday July 18, 2015. Created using Stellarium.
07/16/2015 – Ephemeris – The Summer Triangle is the sign of the season
Ephemeris for Thursday, July 16th. Today the Sun will be up for 15 hours and 12 minutes, setting at 9:25. The Moon, 1 day past new, will set at 9:32 this evening, and tomorrow the Sun will rise at 6:13.
We’re almost a month into summer, and the asterism or informal constellation called the Summer Triangle can be seen midway up the sky in the east as it gets dark. Highest of the three bright stars is Vega in the constellation Lyra the harp, whose body is seen in a narrow parallelogram nearby. The second star of the triangle is Deneb lower and left of Vega, It appears dimmer than Vega because it is by far the most distant of the three. The third star of the Summer Triangle is seen farther below and a right of Vega. It is Altair in Aquila the eagle, and the closest. Altair is 16.5 light years away, Vega is 27 light years while Deneb is so far away that it’s distance is in some doubt and may be 2,600 light years away.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Summer Triangle. Created using Stellarium.
07/09/2015 – Ephemeris – The first stars to appear at night
Ephemeris for Thursday, July 9th. Today the Sun will be up for 15 hours and 23 minutes, setting at 9:29. The Moon, 1 day past last quarter, will rise at 2:05 tomorrow morning, and tomorrow the Sun will rise at 6:07.
Let’s check out all the bright stars in the evening sky, as it gets dark tonight. Low in the west are the planets Venus and Jupiter. High in the west is the bright yellow-orange star Arcturus. In the northwest is the Big Dipper, whose curved handle points to Arcturus. Straightening that curve to a spike will point to Spica a blue-white star low in the southwest. The planet Saturn is located in the south. Below and left of it is the red star Antares which usually twinkles merrily. High in the east is the bright white star Vega. To its lower right is Altair, and to its lower left the star Deneb. Vega, Altair and Deneb make the Summer Triangle, whose rising in the east signals the coming of summer.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
I talked about seeing the first stars a month ago. It seems that in holding star parties this time of year we spend a lot of time watching the first stars appear. I wanted to discuss the Summer Triangle, but it wandered off to what you see above. I’ll get there next week, I promise.
The first stars and planets to appear. See if you can located them from the text. Created using Stellarium for about 10 p.m., July 9, 2015.
06/12/2015 – Ephemeris – The first stars to appear at night
Ephemeris for Friday, June 12th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28. The Moon, 3 days past last quarter, will rise at 4:03 tomorrow morning. Tomorrow the Sun will rise at 5:56.
Evening twilight lasts a very long time this time of year, so the stars will come out slowly. By about a half hour after sunset the planets Venus and Jupiter should be visible in the west. Probably the first actual star to appear is very high in the east, the orange star Arcturus in the constellation of Boötes, which is the 4th brightest night-time star. Next, lower in the northeast, is the 5th brightest star the white Vega in Lyra the harp. By this time Saturn should appear low in the southeast as a yellowish star. Soon many more stars will become visible with the Big Dipper overhead pointing to Polaris in the north, blue-white Spica in the south, Regulus, left of Jupiter and Capella low in the northwest.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The first stars to appear after sunset. This is created from Stellarium for a half hour after sunset. It’s a bit optimistic, in my view, though my eyes aren’t the best. Try your eyes. Click on image to enlarge.
04/20/2015 – Ephemeris – The Lyrid meteor shower will reach peak Wednesday evening
Ephemeris for Monday, April 20th. The Sun rises at 6:50. It’ll be up for 13 hours and 43 minutes, setting at 8:33. The Moon, 2 days past new, will set at 10:57 this evening.
This week the Lyrid meteor shower will reach its peak. The expected peak will be Wednesday the 22nd at 8 p.m. (24 hr UT). Unfortunately the radiant point will not have risen by then. The radiant, near the star Vega in the constellation of Lyra will rise in the northeast by 10 p.m. It will approach the zenith by 6 a.m. as morning twilight brightens. The normal peak hourly rate is about 18 when the radiant is at the zenith, This year it could be as many as 90 per hour. However Europe and Asia will be prime locations to view the shower near the zenith at peak. The shower is caused by the debris of Comet Thatcher, seen only once in 1861. When comets approach the Sun they shed gas, dust and small bits of rock. When the Earth passes through it we get a meteor shower.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Lyrid meteor radiant is near Lyra and the bright star Vega. Th bright star by “Lyr” is Vega. Create by Bob Moler’s LookingUp program.
11/24/2014 – Ephemeris – The Summer Triangle is still with us
Ephemeris for Monday, November 24th. The sun will rise at 7:50. It’ll be up for 9 hours and 16 minutes, setting at 5:07. The moon, 2 days past new, will set at 7:29 this evening.
Well it’s almost Thanksgiving and about time that the Summer Triangle of bright summer stars finally set. Except it won’t go just yet. The stars Vega, Altair and Deneb are still hanging around in the west. The bright summer part of the Milky Way is gone. The constellations the three stars are in are Altair in Aquila the Eagle, now flying vertically up, Deneb in Cygnus the swan flying vertically down, and Vega in Lyre the harp, lying on its side. Altair the southernmost of these three will set first, later Vega will also set. What happens to Deneb depends on your location in the Interlochen Public Radio area. It you are north of Traverse City, Deneb will not actually set over Lake Michigan’s northern horizon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle at 9 p.m. on November 24, 2014. Created using Stellarium.
Vega near its setting point at 11:07 p.m. p.m. on November 24, 2014. Created using Stellarium.
Deneb near its setting point at 5:05 a.m. p.m. on November 25, 2014. Created using Stellarium.
But will Deneb really set for Traverse City. Geometrically it will. However with a flat northern horizon looking northward over the bays to a clean Lake Michigan horizon, atmospheric refraction will bend the light from Deneb making it appear higher in the sky than it really is, so it won’t actually set. On the other side atmospheric extinction, the dimming of stars close to the horizon due to the filtering effect of looking through so much atmosphere would make Deneb impossible to see without a telescope. It might be an interesting challenge to spot.
Bob Moler's Ephemeris Blog 