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06/29/2017 – Ephemeris – A closer look at the star Vega

June 29, 2017 1 comment

Ephemeris for Thursday, June 29th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:31, and it will rise tomorrow at 6:00. The Moon, 1 day before first quarter, will set at 1:21 tomorrow morning.

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 a Kuiper belt of its own. Due to the slow wobble of the earth’s axis Vega will be our pole star in 14 thousand years.

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

Addendum

Lyra

Magnified view of Lyra. Created using Stellarium.

Vega

Vega in the mid-infrared from the Spitzer Infrared Satellite. Credit: NASA/JPL-Caltech/University of Arizona.

Categories: Ephemeris Program, stars Tags: ,

06/27/2017 – Ephemeris – Arcturus as a look at the Sun’s future

June 27, 2017 1 comment

Ephemeris for Tuesday, June 27th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:31, and it will rise tomorrow at 5:59. The Moon, 3 days before first quarter, will set at 12:18 tomorrow morning.

With the Moon brightening the night sky, let’s take a look at the star Arcturus, which with its pointer, the curve of the Big Dipper’s handle is slipping into the high western sky. Arcturus is the 4th brightest night time star, though some think the star Vega, high in the east is brighter. They are different colors because Arcturus is orange, while Vega is whiter than the Sun. Arcturus is a preview of what the Sun will become in four or five billion years from now. It is only 10% more massive than the Sun and is that much older than the Sun, so it is turning into its red giant stage, after running out of hydrogen to turn into helium in its core to produce energy. The helium is now compressing and heating to begin its reaction.

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

Addendum

Arcturus finder chart

Arcturus finder chart with the Big Dipper and Vega as guide posts. Created using Stellarium.

Here’s one of my prior posts about Arcturus, about its great space velocity:  https://bobmoler.wordpress.com/2016/04/26/04262016-ephemeris-arcturus-just-passing-through/

06/26/2017 – Ephemeris – Latest sunset and the apparent positions of the Summer Triangle stars

June 26, 2017 1 comment

Ephemeris for Monday, June 26th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:31, and it will rise tomorrow at 5:59. The Moon, 3 days past new, will set at 11:40 this evening.

Tonight we have the latest sunset of the year. From now on until December sunsets will become earlier. Other than the sunrise and sunset numbers, we’ll begin to notice it for real in a few weeks. At first that realization strikes me a sad note that summer is beginning to end. However the astronomer in me realizes that means more night-time hours, and that the summer Milky Way is coming. Of the three bright stars of the Summer Triangle overhead and in the east, two of its stars are in the milky band. They are Deneb to the north and Altair to the south. Vega, closest to the zenith is not in the band. Actually all the stars we see with the naked eye or small telescopes belong to the Milky Way galaxy.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The constellations Lyra, Cygnus and Aquila

Looking at the stars of the Summer Triangle and their location in and near the Milky Way band. Created using Stellarium.

06/22/2017 – Ephemeris – Now that it’s summer, lets check out the Summer Triangle

June 22, 2017 1 comment

Ephemeris for Thursday, June 22nd. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 1 day before new, will rise at 5:45 tomorrow morning.

We’re a day into summer, and the asterism or informal constellation called the Summer Triangle can be seen rising 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 may be a whopping 2600 light years away. One light year is 6 trillion miles (9 trillion km).

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

Addendum

The Summer Triangle July 5, 2012 at 11 p.m. Created using Stellaruim and The Gimp.

The Summer Triangle. Created using Stellarium and The Gimp.

06/13/2017 – Ephemeris – I call Antares the UFO star

June 13, 2017 Comments off

Ephemeris for Tuesday, June 13th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, half way from full to last quarter, will rise at 12:22 tomorrow morning.

Last week I was observing and showing another person the sky when she remarked about that star low in the sky. That star happened to be Antares, which I call the UFO star. This is a red giant star which in Interlochen and Traverse City never rises above 19 degrees over the southern horizon. It is located in the heart of the constellation Scorpius the Scorpion. With the turbulence in the Earth’s atmosphere, being more marked for objects low in the sky, Antares twinkles mightily. And also being low in the sky, the atmosphere also breaks Antares’ light into a rainbow of colors which, under binocular and telescopic magnification can give the appearance of a multicolored sparkler.

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

Addendum

Antares, Saturn and Jupiter

The star Antares in the heart of Scorpius and the planets Saturn and Jupiter at 11 p.m., June 1, 2017. Created using Stellarium.

Antares

The star Antares in long exposure in this image probably taken from farther south than here. Source unknown, however because the star has four diffraction spikes the photograph was taken with a reflector telescope whose secondary mirror is supported by a 4 vane “spider”.

Categories: Ephemeris Program, stars Tags: ,

02/16/2017 – Ephemeris – The Winter Circle

February 16, 2017 Comments off

Ephemeris for Thursday, February 16th.  The Sun will rise at 7:40.  It’ll be up for 10 hours and 32 minutes, setting at 6:12.  The Moon, 2 days before last quarter, will rise at 12:17 tomorrow morning.

The winter skies are blessed with more first magnitude stars than any other season.  These are the twenty-one brightest stars in the sky.  Six of these stars lie in a large circle centered on the seventh.  This circle is up all evening now that we are in the heart of winter.  Starting high overhead is Capella in Auriga the charioteer.  Moving clockwise, we come to 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 Orion’s large hunting dog, lowest of these stars in the south.  Moving up and left there is Procyon in Canis Minor, Then above it is Pollux in Gemini the twins.  All are centered on Betelgeuse in Orion.

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

Addendum

The Winter Circle of 1st magnitude stars

The Winter Circle of 1st magnitude stars. Created using my LookingUp program.

02/13/2017 – Ephemeris – The brightest night-time star has a tiny stellar companion

February 13, 2017 Comments off

Ephemeris for Monday, February 13th.  The Sun will rise at 7:45.  It’ll be up for 10 hours and 23 minutes, setting at 6:08.  The Moon, 3 days past full, will rise at 9:16 this evening.

Sirius is the brightest night-time star and is located in the south at 9 p.m. below and a bit left of Orion the Hunter.  We’ve visited Sirius last week.  But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. It’s Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title.  The tiny star was suspected as far back as 1834 due to Sirius’ wavy path in the sky against the more distant stars.  Sirius is only 8 light years away.  Sirius A and the Pup have 50 year orbits of each other.  The star was first seen by Alvan Clark in 1862 while testing a new telescope.  The Pup was the first of a new class of stars to be discovered, white dwarfs.  The Pup is about the size of the Earth, with the mass of our Sun; its out of fuel and slowly collapsing.

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

Addendum

Sirius' path

Sirius A & B’s path in the sky showing the wobble that betrayed the Pup’s presence. Credit Mike Guidry, University of Tennessee.

Sirius A and B

Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.

Orion's Belt points to Sirius

Orion’s Belt points to Sirius. Created using Stellarium.