07/31/2015 – Ephemeris – Looking ahead at August in the skies

Ephemeris for Friday, July 31st.  The Sun rises at 6:27.  It’ll be up for 14 hours and 42 minutes, setting at 9:10.   The Moon, at full today, will rise at 9:08 this evening.

Let’s look ahead at the month of August which starts tomorrow.  Daylight hours will decrease from 14 hours and 40 minutes tomorrow to 13 hours 18 minutes on the 31st.  The altitude of the sun at local noon, that is degrees of angle above the horizon will decrease from 63 degrees tomorrow to just over 53 degrees on the 31st.  Straits area listeners can subtract one more degree from those angles.  Local noon, when the sun is due south, is about 1:43 p.m.  The Perseid meteor shower will reach its peak at about 2 a.m. on the morning of the 13th, and should be spectacular with a nearly new Moon.  On the nights between now and then when the moon has set these meteor numbers will be building to the peak.  Saturn will be our only easily visible evening planet.

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

Addendum

Star Chart for August 2015. Created using my LookingUp program.  Click on image to enlarge.The Moon is not plotted.

The planets and stars are plotted for the 15th at 10 p.m. EDT.  That is chart time.  Note, Traverse City is located 1 hour 45 minutes behind our time meridian.  To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.

Evening Astronomical twilight ends at 11:12 p.m. EDT on August 1st, decreasing to 10:06 p.m. EDT on the 31st.

Morning astronomical twilight starts at 4:24 a.m. EDT on August 1st, and increasing to 5:18 a.m. EDT on the 31st.

Add a half hour to the chart time every week before the 15th and subtract and hour for every week after the 15th.

For a list of constellation names to go with the abbreviations click here.

The green pointer from the Big Dipper is:

• Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
• Drill a hole in the bowl of the Big Dipper and the water will drip on the back of Leo the Lion.
• Follow the arc of the Big Dipper’s handle to Arcturus
  • Continue with a spike to Spica
• The Summer Triangle is shown in red
• PerR in yellow is the Perseid radiant

Calendar of Planetary Events

Credit:  Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC)

To generate your own calendar go to http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html

Times are Eastern Daylight Time on a 24 hour clock.  Some additions made to aid clarity.

Conjunctions like the Mercury-Regulus: 0.9° N means Regulus will appear 0.9° north of Mercury.

Aug	01	Sa		Venus: 21.5° East of the Sun
	02	Su	06:11	Moon Perigee: 362,100 km
	03	Mo	22:53	Moon Descending Node
	06	Th	22:03	Last Quarter
	07	Fr	13:25	Mercury-Regulus: 0.9° N
	08	Sa	19:22	Moon-Aldebaran: 0.7° S
	10	Mo	07:11	Moon North Dec.: 18.3° N
	13	Th	02:17	Perseid Shower: ZHR* = 90
	14	Fr	10:54	New Moon
	15	Sa	15:19	Venus Inferior Conjunction with the Sun
	16	Su	10:34	Moon-Mercury: 2.2° N
	17	Mo	19:05	Moon Ascending Node
	17	Mo	22:33	Moon Apogee: 405,900 km
	19	We	23:35	Mars-Beehive: 0.5° S
	22	Sa	13:21	Moon-Saturn: 2.8° S
	22	Sa	15:31	First Quarter
	24	Mo	23:44	Moon South Dec.: 18.2° S
	26	We	17:04	Jupiter Conjunction with the Sun
	29	Sa	14:35	Full Moon
	30	Su	11:24	Moon Perigee: 358,300 km
	31	Mo	06:16	Moon Descending Node
	31	Mo	22:12	Neptune Opposition from the Sun
Sep	01	Tu		Venus: 25° West of the Sun

*ZHR – Zenithal Hourly Rate:  Approximate number of meteors per hour when the shower radiant is at the zenith.  For more information on this and other meteor showers in 2015 see the International Meteor Organization website calendar section: http://www.imo.net/calendar.

07/30/2015 – Ephemeris – Pluto’s enigmatic atmosphere

Ephemeris for Thursday, July 30th.  The Sun rises at 6:26.  It’ll be up for 14 hours and 44 minutes, setting at 9:11.   The Moon, 1 day before full, will set at 6:45 tomorrow morning.

The last image released last week from the New Horizons spacecraft was a stunning one.  It was Pluto backlit, showing a glow completely around the planet, the atmosphere, showing layers.  Also when New Horizons went behind the planet and again went behind Charon from the Earth’s point of view.  Beams of radio waves from seven of the antennas of NASA’s Deep Space Network were sent toward Pluto and New Horizons four and a half hours earlier.  The spacecraft turned its antenna toward Earth and listened.  As the radio waves passed through the atmosphere of Pluto they were refracted and distorted giving clues to the state of the atmosphere.  First takeaway is that Pluto’s atmosphere appears to be collapsing with its increasing distance from the Sun.

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

Addendum

Looking back at Pluto backlit by the Sun from 1.25 million miles. Credits: NASA/JHUAPL/SwRI.

Click here for more information on the above image.

Data from the Alice ultraviolet instrument when Pluto occulted the Sun. Credits: NASA/JHUAPL/SwRI.

Click here for more information on this Alice observation.

07/29/2015 – Ephemeris – Where are the bright planets tonight

Ephemeris for Wednesday, July 29th.  The Sun rises at 6:25.  It’ll be up for 14 hours and 47 minutes, setting at 9:12.   The Moon, 2 days before full, will set at 5:36 tomorrow morning.

Lets take a look at the bright planets for this week.  Our evening stars Venus and Jupiter are together in the west by 9:30 p.m. with Jupiter above and right of Venus.  Venus will set at 9:46 with Jupiter 23 minutes later.  Venus will slide down to the Sun faster and faster in the coming weeks leaving Jupiter behind for a while.  Venus will take 17 days to slide past the Sun.  Jupiter though will take 28 days, so Venus will pass it again around August 4th when both are too close to the horizon and Sun to spot.   There’s a third conjunction of these two in October in the morning sky with Mars nearby.  Saturn is in the south in the evening twilight.  It will set at 1:48 a.m.  Even small telescopes can see Saturn’s rings.

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

Addendum

Venus and Jupiter low on the western horizon at 9:30 p.m. on July 29, 2015. This will be their last appearance on this blog in the west this year. We’ll wait until they appear in the east in the morning. For Venus it’ll be sooner than you think. Created using Stellarium.

Saturn with the bright Moon and some stars of summer in the constellations Scorpius and Sagittarius at 10:30 p.m. July 29, 2015. Created using Stellarium.

Comparative apparent sizes of the evening planets as seen through a telescope of the same magnification on July 29, 2015. Created using Cartes du Ciel (Sky Charts). Note that I didn’t show the moons of Jupiter which are not visible in the bright twilight. Also the program didn’t extend the cusps of Venus’ crescent properly.

This is a chart showing the sunrise and sunset skies for July 29, 2015 showing the location of the planets at that time. Created using my LookingUp program.

07/28/2015 – Ephemeris – The first close up images of Pluto

Ephemeris for Tuesday, July 28th.  The Sun rises at 6:24.  It’ll be up for 14 hours and 49 minutes, setting at 9:13.   The Moon, 3 days before full, will set at 4:32 tomorrow morning.

Two weeks ago the New Horizons spacecraft zipped through the Pluto system gathering a wealth of information including a whole host of images.  Due to their large size the images will take some time to be sent back, however some highly compressed images have been returned and yield a tantalizing look at the dwarf planet Pluto and its large moon Charon.  Rather than an apparently dead heavily cratered body, the first images presented a young surface with plains and mountains with nary a crater to be found.  Young is relative, perhaps 100 million years old or so and implied heating where there appears no source to be found… yet.  The first of many mysteries.  And we have 16 months more  of data and images to be returned.

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

Addendum

First closeup picture the New Horizon Team showed. Two mile high ice mountains, plains, and interesting terrain, but no craters. A young surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.  Click on image to enlarge.

Sputnik Planum (Plain) next to the ice mountains showing polygons and troughs, some with hills. This is part of Pluto’s “Heath”. Note the rectangular lossy compression artifacts in the image. An uncompressed version will be downlinked later. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.  Click on image to enlarge.

 

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).

07/24/2015 – Ephemeris – Astronomical viewing opportunities this weekend

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 giant stage.

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

Addendum

Betsie Valley District Library star party 2014.  A crowd gathers to view Saturn and Jupiter.  (Jupiter will be too low this time.)  Credit: Betsie Valley District Library staff.

The GTAS at the Sleeping Bear Dunes National Lakeshore’s Platte River Point, April, 2012. This time there will be leaves on the trees. Credit Eileen Carlisle.

07/23/2015 – Ephemeris – Altair, the nearest star of the Summer Triangle

Thursday, July 23rd.  Today the Sun will be up for 14 hours and 59 minutes, setting at 9:18.   The Moon, 1 day before first quarter, will set at 12:57 tomorrow morning.  Tomorrow the Sun will rise at 6:20.

The southernmost star of the Summer Triangle is Altair, high in the south. The other two stars of the triangle are Vega nearly overhead, and Deneb high in the east. Altair is the closest of the three at a distance of 16.7 light years away. One light year is nearly 6 trillion miles. Altair is 10 times the brightness of the sun. If seen at Altair’s distance, the sun would only be as bright as one of the two stars that flank it. What is rather different about Altair is its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in only 8.9 hours, The CHARA Interferometer at Mt. Wilson has actually imaged its squashed disk in the infrared. Our sun’s a slow poke, taking nearly a month to rotate once.

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.

Aquila the Eagle in the southeastern sky. Created using Stellarium.

Credit: Zina Deretsky, National Science Foundation

07/22/2015 – Ephemeris – Two planets preparing to leave the evening sky

Ephemeris for Wednesday, July 22nd.  Today the Sun will be up for 15 hours and 1 minute, setting at 9:19.   The Moon, 2 days before first quarter, will set at 12:28 tomorrow morning.  Tomorrow the Sun will rise at 6:18.

Lets take a look at the bright planets for this week.  Our evening stars Venus and Jupiter are together in the west by 9:45 p.m. with Jupiter a little above and right of Venus.  Venus will set at 10:22 with Jupiter 11 minutes later.  Venus’ will slide down to the Sun faster and faster in the coming weeks leaving Jupiter behind for a while.  Venus will take 24 days to slide past the Sun.  Jupiter though will take 35 days, so Venus will pass it again around August 4th when both are too close to the horizon and Sun to spot.   There’s a third conjunction of these two in October in the morning sky with Mars nearby.  Saturn is in the south in the  evening twilight.  It will pass due south at 9:27 p.m. and will set at 2:16 a.m.  Even small telescopes can see Saturn’s rings.

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

Addendum

Venus and Jupiter low on the western horizon at 9:45 p.m. on July 22, 2015. Created using Stellarium.

Saturn and the summer zodiacal constellations of Libra, Scorpius and Sagittarius at 10:30 p.m. on July 22, 2015. Created using Stellarium.

The Moon as it might appear in binoculars tonight at 10:30 p.m. (July 22, 2015). Created using Stellarium.

Comparative apparent sizes of the evening planets as seen through a telescope of the same magnification on July 22, 2015. Created using Cartes du Ciel (Sky Charts).

This is a chart showing the sunrise and sunset skies for July 22, 2015 showing the location of the planets at that time. Created using my LookingUp program.

 

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

07/20/2015 – Ephemeris – July 20th anniversaries

Ephemeris for Monday, July 20th.  Today the Sun will be up for 15 hours and 5 minutes, setting at 9:21.   The Moon, 4 days before first quarter, will set at 11:34 this evening, and tomorrow the Sun will rise at 6:16.

July 20th is a special date for this country’s space program and a personal one.  On July 20, 1969 Apollo 11 landed on the Moon, the greatest achievement in the history of space flight.  Seven years later the robot lander Viking 1 landed on Mars.  NASA wanted it to be July 4th, 1976, the Bicentennial, but couldn’t find a smooth landing site in time.  My own connection to the date came in 1963, my first total solar eclipse. We traveled to Quebec province along side the St. Maurice River. To view 60 seconds of totality.  It was the first of four successful total solar eclipse trips I’ve been on..  I’m looking forward to my 5th on August 21st 2017, two years from now which is related to my first, I’ll tell you about that in my blog.

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

Addendum

Neil Armstrong about to step off the LM onto the surface of the moon, July 20, 1969. Credit: NASA.

First image sent back from Viking 1 after landing on Mars, July 20, 1976. Credit: NASA/JPL.  Click on image to enlarge.

Video of July 20, 1963 eclipse from the air. I got only one picture of the eclipse and it wasn’t very good.  https://www.youtube.com/watch?v=OT3EW0KIjCc.

The date on the YouTube page is incorrect.  It is July 20, 1963.  I remember the corona being somewhat wedge-shaped, wider to one side than the other.  Other than that it was a typical quiet sun corona.

In the program above I mentioned that the August 21, 2017 solar eclipse was related to my first total solar eclipse.  This is the relationship:  A couple of centuries BC the Chaldean astronomers of ancient Babylonia discovered that eclipses repeated in a cycle lasting 6,585 1/3 days.  That’s 18 years 10 or 11 and 1/3 days depending on the number of leap years spanned.  That period was called the Saros by Sir Edmund Halley or comet fame.  So each eclipse would be visible 1/3 of the Earth farther west.  Note that there are many Saros cycles occurring at the same time, and that eclipses of a particular Saros gradually move northward or southward.  So to have an eclipse recur at the approximate same longitude one must wait 3 Saros cycles. or 54 years and one month approximately.  Thus the third Saros of the July 20, 1963 total solar eclipse will be August 21, 2017.  This Saros series (145) is moving southward.  In 1963 it crosses the US at Alaska and Maine.  Quebec was closer for us, s we went there.  Good thing too.  Maine was clouded and rained out.  For us the clouds parted at the beginning of the eclipse.  The 2015 eclipse will cross the continental US from Oregon to South Carolina.

A squished image of the July 20, 1963 eclipse path.  Right click on the image and select view image to get a correct image.  (works in Firefox).

 

A squished image of the August 21, 2017 eclipse path.  Right click on the image and select view image to get a correct image.  (works in Firefox).