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

July 30, 2015 Leave a comment

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

Pluto's halo

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.

Alice Data on the atmosphere of Pluto

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

July 29, 2015 Leave a comment

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 & Jupiter

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.

Moon and Saturn

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.

Apparent sizes of the planets

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.

Sunrise/Sunset

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

July 28, 2015 Leave a comment

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

Ice Mountains

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

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?

July 27, 2015 Leave a comment

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

The Summer Triangle. Created using Stellarium and The Gimp.

Deneb & North American Nebula

One of my old photographs of Deneb and the North American Nebula digitized from a slide.

H-R diagram

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

July 24, 2015 Comments off

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

A  crowd gathers to view Saturn and Jupiter.

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.

GTAS at Sleeping Bear Dunes

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

July 23, 2015 Comments off

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

The Summer Triangle. Created using Stellarium and The Gimp.

Aquila

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

Altair

Credit: Zina Deretsky, National Science Foundation

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

July 22, 2015 2 comments

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

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

Saturn

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

Moon

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

Comparative planet sizes

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).

Sunrise/sunset planets

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.

 

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