02/12/2016 – Ephemeris – A circle of bright stars in winter

February 12, 2016 Leave a comment

Ephemeris for Friday, February 12th.  The Sun will rise at 7:48.  It’ll be up for 10 hours and 18 minutes, setting at 6:06.   The Moon, 3 days before first quarter, will set at 11:19 this evening.

The winter skies are blessed with more first magnitude stars than any other season.  With the moon out these stars will stand out even more, as dimmer stars are suppressed.  Six of these stars lie in a large circle centered on the seventh, the Winter Circle.

This circle is up at 9 p.m.  Starting high nearly overhead is Capella in Auriga the charioteer.  Moving clockwise down to the south, we come to Aldebaran in the face of Taurus the Bull.  Then down to Orion’s knee we find Rigel.  Down and left is the brightest star of all Sirius in Canis Major Orion’s large hunting dog, lowest of these stars in the southeast.  Moving up and left there is Procyon in Canis Minor,  Above is Pollux in Gemini the twins.  All are centered on Betelgeuse the bright red star in Orion’s shoulder.

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

Addendum

Winter Circle

The bright stars of winter arrayed in a circle. Created using Stellarium.

Some also see a Winter Triangle consisting of the stars Betelgeuse, Sirius and Procyon.

02/11/2016 – Ephemeris – What do star colors reveal?

February 11, 2016 Leave a comment

Ephemeris for Thursday, February 11th.  The Sun will rise at 7:49.  It’ll be up for 10 hours and 15 minutes, setting at 6:05.   The Moon, 3 days past new, will set at 10:06 this evening.

The bright stars of winter have subtle differences in color.  But what do those colors mean?  In stars color is indicative of surface temperature.  From coolest to hottest are red, orange, yellow, and white to blue, the hottest.  Interior decorators may disagree, but that’s how it is.  Coolest of the bright stars is red Betelgeuse in Orion’s shoulder, then orange Aldebaran in the face of Taurus the bull, and Pollux in Gemini.  Hotter yet is yellow Capella in Auriga the Charioteer, about the temperature of the Sun.  Then we come to the white-hot Procyon and Sirius in the little and big dogs of Orion.  Hottest is blue-white Rigel in Orion’s knee.  There are hotter stars in Orion, the center and rightmost stars of Orion’s belt are bluer and hotter yet.

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

Addendum

Bright stars of winter

Bright stars of winter with hints as to their colors.  The star label is the color of the star. Created using Stellarium.

Color vs. Surface Brightness

A table of star color and surface temperatures. Created from data in Wikipedia.

The star Alnilam is the center star of Orion’s belt, while Mintaka is the rightmost star of the belt.  The temperature scale K is the Kelvin scale which is the Celsius scale plus 273.15.  Zero on the Kelvin scale is absolute zero.  1 degree Celsius equals 1 Kelvin.  One never says degrees Kelvin.

Betelgeuse is a variable star, so its surface temperature varies.

Categories: stars Tags: ,

02/10/2016 – Ephemeris – The morning planet gang will be around for 9 more days

February 10, 2016 Leave a comment

Ephemeris for Ash Wednesday, Wednesday, February 10th.  The Sun will rise at 7:51.  It’ll be up for 10 hours and 12 minutes, setting at 6:03.   The Moon, 2 days past new, will set at 8:53 this evening.

Let’s check out the whereabouts of the bright naked eye planets.  All the classical planets visible from antiquity are officially now in the morning sky.  However Jupiter actually will rise  at 8:29 p.m., in the east.  Jupiter is still a morning planet since it’s not up at sunset.  Mars will rise next at 1:35 a.m. in the east-southeast.  It’s brighter than the bright star Spica growing even farther to the right of it..  Saturn will rise at 3:40 a.m. in the east-southeast.  Venus will rise at 6:25 a.m. again in the east-southeast.  Mercury will rise behind Venus at 6:39.  Comet Catalina is up all night and is a binocular object in the dark expanse of the constellation Camelopardalis between the bowl of the Big Dipper and the constellation of Perseus.

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

Addendum

Jupiter in the evening sky

Jupiter low in the east-southeast at 10 p.m. on February 10th, 2016. Created using Stellarium.

Jupiter and Moons

Jupiter and its moons as they would be seen in a telescope, at 10 p.m. February 10, 2016. Created using Stellarium.

Morning Planets

The planets in the morning sky at 7 a.m. on February 11, 2016. Jupiter is far to the west. Created using Stellarium.

Saturn and moons

Saturn and its large satellite Titan and other moons as they should appear in a telescope at 7 a.m. February 11, 2016.

Comet Catalina

Comet Catalina’s path for the next week. Note that it is fading fast. It will take binoculars or a small telescope to spot the comet which will not show a tail visually. Created using Stellarium.

Planets at sunrise and sunset

This is a chart showing the sunrise and sunset skies for February 10, 2016 showing the location of the planets, the Moon and Comet Catalina at that time. Created using my LookingUp program.

Some of these images above are shown smaller than actual size.  Image expansion lately hasn’t worked.  If you are using Firefox, right-click on the image, and then click on View Image.

02/09/2016 – Ephemeris – The Dog Star has a pup

February 9, 2016 Leave a comment

Ephemeris for Fat Tuesday, Tuesday, February 9th.  The Sun will rise at 7:52.  It’ll be up for 10 hours and 9 minutes, setting at 6:02.   The Moon, 1 day past new, will set at 7:39 this evening.

Sirius is the brightest night time star and is located in the southeast at 9 p.m. below and a bit left of Orion the Hunter.  We’ve visited Sirius once before this winter.  But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. Its name is Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title.  The tiny star was suspected as far back as 1834 due to Sirius’ wavy path against the more distant stars.  Sirius and the Pup have 50 year orbits of each other.  The Pup was first seen by famed 19th century telescope maker Alvan Clark in 1862 while testing a new telescope.  The Pup is a white dwarf star, as small as the Earth but with the mass of the sun, out of hydrogen fuel and slowly collapsing.

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

Addendum

Orion and his hunting dogs

Orion and his hunting dogs revealed in animation. Created with Stellarium and GIMP.

Sirius' path

Sirius A & B’s path in the sky showing the wobble that betrayed the Pup’s presence. Credit Mike Guidry, University of Tennessee.

Sirius A and B

Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.

02/08/2016 – Ephemeris – The celestial unicorn

February 8, 2016 Leave a comment

Ephemeris for Monday, February 8th.  The Sun will rise at 7:53.  It’ll be up for 10 hours and 6 minutes, setting at 6:00.  The Moon is new today, and won’t be visible.

Among all the constellations in the sky of animals real and mythical, there is also a unicorn.  It’s called Monoceros, and inhabits the southeastern sky at 9 p.m. bounded by Orion on the right, Canis Major, the great dog below and Canis Minor, the little dog to the left.  Unfortunately for observers without optical aid Monoceros, though large, is devoid of bright stars.  Maybe that’s why no one sees unicorns anymore.  It has many faint stars because the Milky Way runs through it.  To the telescope it is a feast of faint nebulae or clouds of gas and dust, the birth place of stars, including the red rose of the Rosette Nebula whose central star cluster can be seen in a telescope but the nebulosity requires a camera to capture and store its light.

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

Addendum

Moniceros the unicorn. Created using Stellarium.

Monoceros the unicorn. Created using Stellarium.

Rosette Nebula

Rosette Nebula in the infrared from the Spitzer Space Telescope. Credit: NASA/JPL/Caltech

02/05/2016 – Ephemeris – Women in astronomy night at the GTAS tonight

February 5, 2016 Comments off

Ephemeris for Friday, February 5th.  The Sun will rise at 7:57.  It’ll be up for 9 hours and 58 minutes, setting at 5:56.   The Moon, 3 days before new, will rise at 6:12 tomorrow morning.

Tonight there will be a meeting of the Grand Traverse Astronomical Society at Northwestern Michigan College’s Rogers Observatory, featuring a graduate from NMC and the astronomy program: Becky Shaw who will present a talk Women in Astronomy.  This is a second presentation of more female astronomers, the last was in November I especially recommend this for girls in school interested in the STEM fields, that is Science, Technology, Engineering and Math to find out the wonderful contributions these women have made.  Astronomy, by the way encompasses all the STEM fields.  The meeting starts at 8 p.m. and the observatory is located on Birmley Road, south of Traverse City.  At 9 p.m. the will also be star party if it’s clear.

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

Addendum

Appropriate to our speaker’s topic:  In the news now is Smith’s Cloud, discovered by Gail Smith (now Gail Bieger-Smith) in 1963 as an astronomy student at Leiden University in the Netherlands.   In new studies with the Green Bank (Radio) Telescope and the Hubble Space Telescope the velocity and composition of the cloud has been measured.  It somehow was ejected from the Milky Way some 70 million years ago, but it’s coming back!  In 30 million years it will crash back in, hitting the Milky Way’s other gas clouds and will probably cause a burst of star formation of maybe 2 million new stars.

Smith's cloud

Smith’s cloud superimposed on the Milky Way. Smith’s Cloud is only visible at radio wavelengths, while the Milky Way shown is a visible photograph. Credit: Saxton/Lockman/NRAO/AUI/NSF/Mellinger.

02/04/2016 – Ephemeris – Orion is visible from everywhere

February 4, 2016 Comments off

Ephemeris for Thursday, February 4th.  The Sun will rise at 7:58.  It’ll be up for 9 hours and 56 minutes, setting at 5:55.   The Moon, half way from last quarter to new, will rise at 5:21 tomorrow morning.

The constellation of Orion the hunter is now due south at 9 p.m. It is an upright rectangle of bright stars, the shoulders and knees of this giant.  In the center are three stars in a straight line, his belt, and from his belt hangs a sword.  Orion is the most famous of all constellations world-wide, due to its bright stars, and straddles the celestial equator, so that it is visible at least in part from pole to pole.  It contains the closest star forming region to us, the Great Orion Nebula seen easily in his sword with binoculars or small telescope.  The Horse Head Nebula is found below the left belt star, but only in photographs.  Another photographic feature is Barnard’s Loop, the partial shell of an ancient supernova to the left of Orion.

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

Addendum

Otion as seem from most of the Earth

Orion from mid latitudes north of the equator. Orion would be upside down if viewed south of the equator. Created using Stellarium.

Orion from near the north pole.

Orion from near the north pole. Created using Stellarium.

Orion from near the south pole

Orion from near the south pole. Created using Stellarium.

Orion's Nebulae

The nebulae in Orion including the Great Orion Nebula in the sword, the Horse Head Nebula below the leftmost star of Orion’s Belt named Alnitak. Barnard’s loop is the big arc on the left. Just above Alnitak is the Flame Nebula, I neglected to mention it in the program. It can be spotted in a telescope, especially if Alnitak is moved off the edge of the field of view. Credit Rogelio Bernal Andreo, via Wikipedia.

Note the nebula at the lower right.  It’s the Witch’s Head Nebula, which I believe is shown brighter than it actually is.  It’s being illuminated by the blue giant star Rigel to the left of it.

 

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