Archive
11/07/2014 – Ephemeris – GTAS meeting tonight and Star Party
Ephemeris for Friday, November 7th. The sun will rise at 7:28. It’ll be up for 9 hours and 55 minutes, setting at 5:23. The moon, 1 day past full, will rise at 6:15 this evening.
Tonight the Grand Traverse Astronomical Society will hold their monthly meeting at he Northwestern Michigan College’s Rogers Observatory at 8 p.m. featuring yours truly presenting the Hitchhikers Guide to the Solar System. I have found, what NASA and other space agencies have found, that once orbiting the Sun in the solar system. One can go anywhere in the solar system with a minimum of energy, if one has the time. We’ll start by looking at orbits about the Earth and how they can be changed. We’ll look at escape velocity and those seemingly strange Lagrangian points, plus stealing energy from the planets. At 9 p.m. there will be a star party featuring the Moon and some of the brighter deep sky objects. The observatory is located on Birmley road.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Artist’s concept of interplanetary superhighway or Interplanetary Transport Network. Credit: NASA/JPL.
07/10/2014 – Ephemeris – Why is the bright Moon so low in summer and so high in winter?
Ephemeris for Thursday, July 10th. Today the sun will be up for 15 hours and 20 minutes, setting at 9:28. The moon, 2 days before full, will set at 5:22 tomorrow morning. Tomorrow the sun will rise at 6:08.
If you watch the moon for the next few nights, you won’t have to strain your neck because the moon at its highest will be less than 30 degrees above the southern horizon for us in northern Michigan. That’s because the moon closely follows the path of the sun in the sky, called the ecliptic, with a deviation of only 5 degrees maximum. Tonight it’s a couple of degrees north of the ecliptic. Tonight it’s located about where the sun was back last November or will be next November. In winter you’d swear that the full moon at its greatest height was practically overhead. It’s another effect of the Earth’s axial tilt of 23 ½ degrees. Our moon is odd in it doesn’t orbit the Earth’s equator like most large moons do for their planets.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The full Moon on July, 12, 2014. Created using Stellarium.
The full Moon on December 6, 2014. Created using Stellarium.
06/16/2014 – Ephemeris – Dates of the earliest sunrise and latest sunset
Ephemeris for Monday, June 16th. Today the sun will be up for 15 hours and 33 minutes, setting at 9:29. The moon, half way from full to last quarter, will rise at 12:11 tomorrow morning. Tomorrow the sun will rise at 5:56.
Yesterday saw the earliest sunrise for the year. My sunrise times will start to show a change on Thursday. The day-to-day change in sunrise times are now a few seconds. The summer solstice, or longest day will be this Saturday, and the latest sunset won’t occur until next week Thursday. The reason these dates don’t coincide has to do with the tilt of the earth’s axis and the earth’s slightly elliptical path around the sun. Actually the disparity between these dates is more pronounced at the winter solstice when the Earth is closer to the sun and moving faster. Yup, the sun is farther away now than it was in December. Actually we’re moving slower now, so summer lasts a few days longer than winter.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
06/12/2014 – Ephemeris – Jupiter is making up for lost time and is heading rapidly eastward
Ephemeris for Thursday, June 12th. Today the sun will be up for 15 hours and 31 minutes, setting at 9:28. The moon, 1 day before full, will set at 6:38 tomorrow morning. Tomorrow the sun will rise at 5:56.
The planet Jupiter which is the brilliant star-like object in the west is starting to pick up its eastward motion in the stars. Several months ago as the earth was passing Jupiter when it was rising in the east at sunset, it had stopped its eastward motion against the stars and headed westward. This retrograde motion was due to Earth in essence passing the slower moving Jupiter. Now that it’s on the other side of the sun Jupiter is making up for lost time because it and Earth are now moving in opposite directions. This I see in the week to week setting times of Jupiter. Stars rise and set 4 minutes earlier each night. For Jupiter its down to three minutes, meaning it’s moving eastward. When we see it again in December it will have blown past Cancer to Leo, but it will later backtrack into Cancer.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter’s apparent motion over the next 180 days. Note by December Jupiter will slow and will begin its retrograde loop as the Earth catches up with it again. Created using Cartes du Ciel (Sky Charts).
03/29/2013 – Ephemeris – How we know this Sunday is Easter
Ephemeris for Good Friday, Friday, March 29th. The sun will rise at 7:28. It’ll be up for 12 hours and 38 minutes, setting at 8:06. The moon, 2 days past full, will rise at 11:14 this evening.
Wednesday was the day of the Paschal full moon, the full moon after the first day of spring, which is defined by Christian churches as March 21st. For the date of Easter the actual full moon isn’t used, but a rather complicated formula is used to find the new moon. There’s a complicated correction to then find the date of the full moon, which 2 days ago. This year that formula works out correctly. It can be a day off either way. The next Sunday then is Easter. Orthodox churches use the Julian calendar and a different formula but they’ll celebrate Easter on May 5th. The formula was set up to approximate the Jewish lunar calendar. It works out close this year because Passover started at sunset last Sunday night.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
03/26/2013 – Ephemeris – The universe is slightly older than we thought
Ephemeris for Tuesday, March 26th. The sun will rise at 7:34. It’ll be up for 12 hours and 28 minutes, setting at 8:02. The moon, 1 day before full, will set at 7:20 tomorrow morning.
Last week NASA and the European Space Agency announced the findings from the Planck satellite. Along with a sharper map of the Cosmic Microwave Background, created at the moment the Universe became transparent some 380,000 years after the Big Bang, Planck data revealed a slightly older universe of 13.82 billion years. This is with the error thought to be in the last measurement. So it’s a refinement. Also the universe appears to be expanding at a slightly lower rate that had been. Of the three main constituents of the universe, ordinary matter out of which you, me and the stars are made of is 4.9 percent, dark matter that holds galaxy clusters together is at 26 percent, while dark energy is at 68.3 percent, a decrease for it.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Cosmic Microwave Background as determined by the Planck satellite. Image credit: ESA and the Planck Collaboration.
02/26/2013 – Ephemeris – Light: Is it particles or waves, or is it both?
Ephemeris for Tuesday, February 26th. The sun will rise at 7:24. It’ll be up for 11 hours and 2 minutes, setting at 6:26. The moon, 1 day past full, will rise at 7:47 this evening.
Yesterday I talked about light in terms of waves and wavelengths. Light has a dual identity because I also acts like particles. They’re called photons. The shorter the wavelength the more energy the photon has. Light’s wave property explains how light is bent when it passes through a lens, and why stars in telescopes have diffraction rings and spikes. However CCD cameras and other light detection devices work because light also is particles. Some are sensitive enough to count photons one at a time. What’s even crazier is that particles like electrons also behave like waves. This is quantum mechanics, the physics of the nano world. Astrophysicists, what professional astronomers really are, work with the micro and the macro universe.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The proof of the pudding, quantum pudding that is, is the famous double slit experiment. There’s a nice animated video on YouTube featuring “Dr. Quantum” to blow your mind about electrons acting like waves. Click here.
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.
02/22/2013 – Ephemeris – Speed of light: hinderance and help
Ephemeris for Friday, February 22nd. The sun will rise at 7:31. It’ll be up for 10 hours and 49 minutes, setting at 6:21. The moon, 3 days before full, will set at 5:55 tomorrow morning.
Yesterday I talked about the invariability of the speed of light in a vacuum. This would seem to put interstellar travel on the list of things that can’t be done. Apparently General Relativity has ways of getting around. I’ll leave that to smarter people to explain. But one cool thing about the speed of light is that it allows us to see into the distant past. The farther the object is away the farther back in time we can see it. With the Hubble Space Telescope in its Deep Field images of galaxies can see back to within perhaps a billion years of the Big Bang, at least for a few galaxies. The James Webb space telescope to be launched later this decade will explore, among other things more deeply into this unknown time to see how these galaxies formed.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
02/21/2013 – Ephemeris – Speed of light
Ephemeris for Thursday, February 21st. The sun will rise at 7:32. It’ll be up for 10 hours and 46 minutes, setting at 6:19. The moon, half way from first quarter to full, will set at 5:21 tomorrow morning.
The speed of light at 186,000 miles a second or 300,000 kilometers a second. It is the ultimate speed limit in the universe. nothing with mass can match is speed. But particles without mass, like photons, travel at that speed in a vacuum naturally. That speed of light in a vacuum was a constant was postulated by Albert Einstein and was the central part of his Special Theory of Relativity published in 1905. In physics the lower case letter c represents the speed of light in a vacuum. And its figures in Einsteins most famous equation, which actually wasn’t part of special relativity: e=mc2. The equation that changed the world for good or ill. Science itself is nether good nor bad. It’s how that knowledge is applied.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Bob Moler's Ephemeris Blog 