05/29/2015 – Ephemeris completes 40 years on the air

May 29, 2015 Leave a comment

Ephemeris for Monday, June 1st.  Today the Sun will be up for 15 hours and 20 minutes, setting at 9:21.   The Moon, 1 day before full, will set at 6:17 tomorrow morning and tomorrow the Sun will rise at 6:00.

We’ll start Ephemeris’ 41st orbit of the Sun by looking at the skies of June.  There’ will be a lot of sun in June and very little night.  The daylight hours will increase a bit from 15 hours and 20 minutes today to 15 hours and 34 minutes on the 21st, retreating back to 15 hours 31 minutes at month’s end.  At this time of the year the sunset times for Ludington, Interlochen, Petoskey and Mackinaw City are very nearly the same.  However the sunrise times are at their most divergent.  With Ludington’s sunrise being 14 minutes later than Mackinaw City’s.  The altitude of the sun above the southern horizon at local noon will hover around 68 to 69 degrees.  Local noon, when the sun is actually due south will occur at about 1:43 p.m.  Here’s what we’ve been waiting for:  Summer will start on the 21st at 12:38 p.m.

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

Addendum

This is my article in the June Stellar Sentinel, the monthly newsletter of the Grand Traverse Astronomical Society

At the end of May I will have completed 40 years of the short program on Interlochen Public Radio (IPR) I call Ephemeris. The first airing was June 1st 1975. It currently airs twice each week day at 7:49 a.m. on their news stations, and at 7:59 a.m. on their classical music stations. This article isn’t about Ephemeris, but what has transpired in the last 40 years. It’s kind of sobering to realize that 40 years is approximately 10% of the span of 406 years since Galileo first turned his crude telescope to the night sky. Over the next year I’ll look at what has been happening in astronomy and space in those 40 years. This time I’ll look at some telescope advances in that time.

In 1975 the largest optical telescope in the world was the Hale 200 inch (5 meter) telescope* on Mount Palomar, today the Keck I telescope and its twin Keck II on Mauna Kea in Hawai’i are among the largest in the world with 10 meter diameter mirrors. Keck I saw first light in 1990, while Keck II saw its first light in 1996. They share the peak with two 8 meter telescopes: Gemini North and Subaru, among other large scopes. The Thirty Meter Telescope (TMT) is about to be built up there pending the clearing up of a dispute with native Hawaiians who consider the mountain sacred.

Actually the Kecks have been edged out by the Gran Telescopio Canarias, in the Canary Islands with a 10.4 meter mirror, which saw first light a few years ago. Not to be outdone, the European Southern Observatory, a consortium of 13 European nations have established a beachhead in the Chilean Andes and are building the European Extremely Large Telescope (E-ELT). Its segmented mirror will span 39.3 meters (1,550 inches), nearly eight times the diameter of the Hale telescope, and is expected to see first light in 2024. If Ephemeris and I will be around another 10 years, we’ll see that too.

Many of the existing large telescopes have been shown up by NASA’s most popular satellite, the Hubble Space Telescope (HST) which has only a 2.4 meter (94.5 inch) mirror. Telescope placement is like real estate: Location, location, location. The higher the better to beat the bane of telescope viewing atmospheric turbulence. Nearly 400 miles altitude in orbit solves that problem nicely. The next generation space telescope is to be launched in three years. It’s the James Webb Space Telescope (JWST), named for an Apollo era NASA administrator. It will be launched by an ESA Ariane 5 rocket to the Earth-Sun L2 point a million miles opposite the direction of the Sun. It will operate in the infrared.

Not to be outdone by Hubble, ground based astronomers have found a way to combat atmospheric turbulence, or “bad seeing” as we term it: It’s called adaptive optics. Ever see those time-lapse videos of the Keck and other observatories shine lasers skyward. These are tuned to the wavelength that excites sodium atoms in the atmosphere above 50 kilometers to produce an artificial star. By deforming the telescope mirror or mirror segments to straighten out the artificial star’s light the atmospheric seeing can be improved by a factor of 16 or better. This technique works better in the infrared whose wavelengths are longer than visible light.

Our atmosphere is relatively transparent at wavelengths that happen to be at the Sun’s peak output. That is where evolution has given us the ability to see in. However to use an acoustic analogy, we are doomed to hear the cosmic symphony by listening to a single octave on a piano that stretches in a mile in either direction from middle C.

In 1975 radio astronomy was beginning to work with multiple telescopes to produce radio interferometers that spanned the continent to produce the effect of a single telescope of the width of the array of many telescopes. These arrays have now spanned oceans, and even into space. These interferometers rival and surpass the resolution of optical telescopes. A prime goal is to resolve the black hole in the center of the Milky Way, something that can’t be seen invisible light, which can’t penetrate the gas and dust along the 26,000 light year path to the center of our galaxy.

Today there are neutrino telescopes underground, X-ray telescopes and Gamma Ray telescopes orbiting the Earth, an armada of spacecraft orbiting and studying the Sun. Also techniques and instruments have been refined, so that when once the idea of detecting planets around other stars was thought to be a dream for the future, we’ve been discovering them by the thousands over the last 20 years. Even amateur astronomers can do it now.

In the 45 seconds I have to devote to astronomical topics after the sunrise, sunset and lunar phase information in an Ephemeris program I cannot delve deeply into the wonders that modern astronomy brings. But I can give a taste, and provide the key to the heavens to just go out and experience the wonder of the universe that is the night sky as seen from our own back yards.

* I forgot about BTA-6 in the Caucasus Mountains in the then Soviet Union, a 6 meter telescope that saw first light in late 1975, so I guess I was still correct on the Ephemeris launch date.  It has a history of problems and was never really able to fulfill its promise for a number of reasons.  It beat out the Hale telescope by 38 inches.  It did pioneer the alt-azimuth mount that all large telescopes now use.

05/28/2015 – Ephemeris – Saturn’s satellites

May 28, 2015 Leave a comment

Thursday, May 28th.  Today the Sun will be up for 15 hours and 14 minutes, setting at 9:17.   The Moon, 3 days past first quarter, will set at 3:56 tomorrow morning and tomorrow the Sun will rise at 6:02.

Saturn has a lot of moons, even if you don’t count the billions of ring particles circling the planet.  The count is up to 62, five short of Jupiter’s 67 at last count.  The largest is Titan which is larger than Mercury, a world with a thick nitrogen atmosphere and liquid filled lakes.  At its distance from the Sun, some 10 times Earth’s and receiving only one percent the heat we get the lakes are filled with methane and ethane while the surface rocks are water ice.  The small moon Enceladus spews salty water geysers at its south pole.  The more distant moon Iapetus is half black and half white and has an equatorial mountain range that rings it like a walnut.  Another moon Hyperion appears like it’s honeycombed.

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

Addendum

Titan's seas

Titan in a false color near infrared view, showing the Sun’s light glinting off a north polar sea. Credit: NASA/JPL.

Enceladus

Enceladus’ south polar geysers create the E ring. Credit: NASA/JPL.

Iapetus

Iapetus showing mostly its dark side and equatorial mountain ridge. Credit: NASA/JPL.

Hyperion

The weird moon Hyperion. It’s half as dense as ice. Credit: NASA/JPL:

05/27/2015 – Ephemeris – Let’s look at the bright planets for this week

May 27, 2015 Leave a comment

Ephemeris for Wednesday, May 27th.  Today the Sun will be up for 15 hours and 12 minutes, setting at 9:16.   The Moon, 2 days past first quarter, will set at 3:28 tomorrow morning and tomorrow the Sun will rise at 6:03.

Lets take a look at the bright planets for this week.    Our brilliant evening star Venus is seen in the west by 9:30 p.m. In telescopes it will appear as a dazzling orb somewhat over half illuminated by the sun.  It will set at 12:46 a.m. Finally it’s beginning to set earlier.  The Sun is catching up with it.  Venus will reach its greatest angular separation from the Sun on June 6th.  Venus is seen below the stars Castor and Pollux in Gemini.  Jupiter will appear high in the west-southwestern sky before 10 p.m.  It will set at 1:48 a.m.  It’s near the sickle-shaped head of Leo the lion.  Saturn will be seen in the east southeastern sky as evening twilight deepens.  It’s in Scorpius this year.

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

Addendum

Evening planets

The evening planets and the Moon from west to east at 10:30 p.m. on May 27, 2015. Created using Stellarium.

Telescopic planets

Apparent sizes of the planets Venus, Jupiter and Saturn compared for 10:30 p.m. on May 27, 2015. Created using Cartes du Ceil (Sky Charts).

Note above that the moon Io will be transiting Jupiter at 10:30 p.m.  It’s shadow is also projected on the planet.  Io will move off the planet at 11:06 p.m., and the shadow event will end at 12:18 a.m.

Moon

Telescopic view of the Moon at 10:30 p.m. on May 27,2015. Created using Virtual Moon Atlas.

05/26/2015 – Ephemeris – Saturn’s Rings

May 26, 2015 Leave a comment

Ephemeris for Tuesday, May 26th.  Today the Sun will be up for 15 hours and 11 minutes, setting at 9:15.   The Moon, 1 day past first quarter, will set at 3:01 tomorrow morning and tomorrow the Sun will rise at 6:03.

The feature that makes Saturn so special are its rings.  While astronomers have found rings around Jupiter Uranus and Neptune plus an asteroid, none are a grand a Saturn’s rings.  Saturn’s rings are made of ice or icy particles, and have a higher reluctance (albedo) than the planet.  Each of the ring particles has a separate orbit over Saturn, and the many collisions have restricted the ring particles to Saturn’s equator.  While the rings are 170 thousand miles wide they are only 30 feet thick. Saturn has an axial tilt of 26 degrees close to the Earth’s 23 ½ degrees, so over Saturn’s nearly 30 year orbit of the sun, the rings go edge on about every 15 years.  That last time was 2009.

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

Addendum

Saturn's rings change.

How the appearance of the rings change as Saturn orbits the Sun. Credit: NASA Hubble.

05/25/2015 – Ephemeris – Venus will appear to approach Jupiter throughout June

May 25, 2015 Leave a comment

Ephemeris for Memorial Day, Monday, May 25th.  Today the Sun will be up for 15 hours and 9 minutes, setting at 9:14.   The Moon, at first quarter today, will set at 2:34 tomorrow morning, and tomorrow the Sun will rise at 6:04.

In a telescope the planet Venus is itself near a half phase.  Of course, Venus orbits the sun, not the Earth.  It will appear about at half illuminated when it’s at its greatest apparent distance from the sun.  Right now Venus is about half the apparent size of Jupiter, but it’s heading our way, so it will grow in apparent size.  On June 30th Venus will pass Jupiter, by then it will appear the same size as Jupiter, and appear less than the diameter of the Moon apart.  There is a coincidence between this conjunction and one over 2,000 years ago, and I’ll be investigating that in another month.  I’ll have hints at the June 5th meeting of the Grand Traverse Astronomical Society.

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

Addendum

Venus-Jupiter conjunction

Telescopic view of Jupiter and Venus at 10:30 p.m. June 30, 2015. The two planets will appear two thirds the width of the Moon apart. Both will fit easily in the field of a 50 power eyepiece. Created using Cartes du Ceil (Sky Charts).

05/22/2015 – Ephemeris – View the Sun and the Planets from the Sleeping Bear Dunes this Saturday

May 22, 2015 Comments off

Ephemeris for Friday, May 22nd.  Today the Sun will be up for 15 hours and 3 minutes, setting at 9:11.   The Moon, 3 days before first quarter, will set at 1:00 tomorrow morning, and tomorrow the Sun will rise at 6:06.

Tomorrow the Grand Traverse Astronomical Society will be at the Sleeping Bear Dunes National Lakeshore for a Sun and Star Party at the Dune Climb.  From 4 to 6 p.m. the Sun will be the attraction.  Besides sunspots, visible in most well filtered telescopes, the society’s solar telescope will show the Sun in the light of hydrogen, showing a much more active part of the Sun.  Starting about 9:30 Venus,  and then Jupiter will appear, followed a bit later by the ringed planet Saturn.  The event will take place only if the weather cooperates and it’s clear or partly cloudy.  The society has scheduled monthly star parties at the Dunes through October plus a special meteor shower watch in August.

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

Addendum

Star party 1

Star Party at the Sleeping Bear Dunes National Lakeshore, Thoreson Farm August 2013. Credit Eileen Carlisle.

Star party 2

Star Party at the Sleeping Bear Dunes National Lakeshore, Thoreson Farm August 2013. Credit Eileen Carlisle.

Sorry we don’t have good pictures of a Dune Climb star party.  The event shown above is near the maximum of the Perseid meteor shower, which is why some folks are carrying blankets.  The Thoreson Farm event is part of the Port Oneida Fair at the Port Oneida Rural Historic District a small farming community on the eastern shore of Sleeping Bear Bay, and within the boundaries of the Sleeping Bear Dunes National Lakeshore.

05/21/2015 – Ephemeris – Saturn will reach opposition tomorrow

May 21, 2015 Comments off

Ephemeris for Thursday, May 21st.  Today the Sun will be up for 15 hours and 1 minute, setting at 9:10.   The Moon, 3 days past new, will set at 12:21 tomorrow morning, and tomorrow the Sun will rise at 6:07.

The Planet Saturn will be at opposition from the Sun tomorrow, meaning that it is opposite the Sun in the sky, rising at sunset and setting at sunrise.  It also means that Saturn is about it’s closest, brightest, and its largest appearing in telescopes.  It will be 835 million miles (1,344 million km) away tomorrow.  It’s rings should also be at their brightest.  The rings are made of billions of particles, mostly ice.  At opposition we are essentially viewing Saturn from the same direction as the Sun, and ring particle shadows on one another disappear, so the rings are brighter.  Other defining shadows also disappear such as the planet’s shadow on the rings and the ring’s on Saturn, so the planet may appear kind of flat.

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

Addendum

Saturn at opposition

Saturn at opposition, May 22, 2015. Compare the shadow of the planet on the rings with the quadrature image below. Created using Cartes du Ceil (Sky Charts).

Saturn near quadrature

Saturn near quadrature, August 23, 2015. Compare the shadow of the planet on the rings with the opposition image above. Created using Cartes du Ceil (Sky Charts).

A superior planet’s quadrature position (90 degrees from the Sun) is the time we are the maximum amount out of line with the Sun from them.  Any phase of shadows are the most pronounced.  From the planet’s point of view the Earth is at greatest elongation from the Sun.

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