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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
06/24/2013 – Ephemeris – Infrared astronomy
Ephemeris for Monday, June 24th. Today the sun will be up for 15 hours and 33 minutes, setting at 9:31. The moon, 1 day past full, will rise at 10:27 this evening. Tomorrow the sun will rise at 5:58.
During most of history astronomers viewed the heavens in visible light. That’s all we had, our eyes, later augmented by telescopes, and photography. Today astronomers view the heavens with a myriad of detectors on the earth, above the earth and inside the earth. Radiation detected, beside visible are radio, infrared, ultraviolet, x-rays, and gamma rays, all part of the electromagnetic spectrum as is visible light. Besides that the observe neutrinos and cosmic rays, and are searching for gravitational waves. An intense field of study now is infrared, which must be observed from high mountaintops or from space. Last year I visited one of those facilities at nearly 14,000 feet altitude the observatories atop Mauna Kea in Hawaii. [Which included the two largest telescopes in the world the twin 10 meter Keck telescopes, Gemini North, Subaru and other telescopes. ]
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The twin domes of the Keck 10 meter telescopes. Left is the Japanese Subaru telescope. Right is the NASA Infrared Telescope facility. Credit: Bob Moler. Click to enlarge.
The 8.1 meter Gemini North telescope dome in the center. To the left is the Canada-France-Hawaii Telescope dome. Credit: Bob Moler.
02/25/2013 – Ephemeris – Electromagnetic spectrum
Ephemeris for Monday, February 25th. The sun will rise at 7:26. It’ll be up for 10 hours and 58 minutes, setting at 6:25. The moon, at full today, will rise at 6:40 this evening.
With the moon so bright I’ve been talking about light our last couple of programs. When I talk about light I’m talking about electromagnetic radiation, its whole spectrum, not the single octave of frequencies that we perceive as visible light. On the long end is radio waves, like those you are hearing me now by, microwaves of radar and those microwave ovens. Then there’s infrared we sense as heat on our skin, and then visible light. Shorter wavelengths and higher frequencies we have ultraviolet, x-rays and finally gamma rays. The final three are harmful to us and our atmosphere generally protects us from it. Astronomers have learned to observe the universe in all those wavelengths. And found a universe that is quite amazing and dangerous.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Electromagnetic Spectrum. Credit: Inductiveload, NASA.
Bob Moler's Ephemeris Blog 