2016: August 25, Mars and Saturn

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With a cloud deck obscuring Jupiter and Venus in the western sky, as seen from the Chicago area, Mars and Saturn shine from the southwest this evening.  Mars is rapidly moving eastward.  Compare its position tonight to where it was a few evenings ago.

Click here for more information about the Venus-Jupiter Epoch Conjunction.

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

2016: August 2016, Diagram Sources

This chart shows the setting times of Venus ,the moon, planets, and stars compared to sunset during the appearance of Venus in the evening sky during 2016-2017. Chart calculated from data by the U.S. Naval Observatory.

This chart shows the setting times of Venus ,the moon, planets, and stars compared to sunset during the appearance of Venus in the evening sky during 2016-2017. Chart calculated from data by the U.S. Naval Observatory.

Charts that are used in these postings are available for use in classrooms and by astronomy clubs in their publications.  Charts are plotted for Chicago, Illinois, Palm Springs, California, and Sacramento, California.  Files are posted here after they are used in these postings and for other professional purposes.  A license is available in the read me file.  The charts are available at http://goo.gl/Sfp1ur

2016: August 22, Venus, Jupiter, Mars & Saturn

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Just 5 days before the Epoch Conjunction of 2016, Venus and Jupiter shine from the western sky this evening as seen from the Chicago area on an unseasonably cool and clear evening.  Tonight pair is 5 degrees apart.   (See this article for more details.)

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Meanwhile Mars, Antares, and Saturn appear near each other in the southwest.  Mars is 2 degrees  from Antares and 4.5 degrees from Saturn.  Watch Mars pass Antares and Saturn this week.

2016: August 16, Venus and Jupiter

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Just 11 days before the Great Venus-Jupiter Epoch Conjunction of 2016, Venus and Jupiter shine from the western sky this evening as seen from the Chicago area. (See this article for more details.) Tonight the pair is 11 degrees apart and closing rapidly.  Venus is very low in the western sky at about 40 minutes after sunset with Jupiter to its upper left.

2016: August 15, Venus and Jupiter

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As Venus emerges from the sun’s brilliant glare, it is 12 days before the Venus-Jupiter Epoch Conjunction of 2016 with the two appear to pass fractions of a degree apart.  (See this article for more details.)  Tonight Jupiter and Venus are 12 degrees apart.  Mercury is nearly in between them.  It is rapidly disappearing into the sun’s glare.  Mercury appears in the morning sky, making its morning appearance of the year in late September and early October.

The chart above shows the planets at 8:30 p.m. CDT as seen from the Chicago area.  For your local circumstances, look west about 40 minutes after sunset.  Venus is very low in the western sky.  Binoculars may be need to first locate it.  It is easily spotted without optical aid once it is located.  Jupiter is the bright star to the upper left of  Venus.  Locate Mercury with binoculars.

2016, August 12: Perseid Meteor Shower

Milky Way and Exploding Meteor
Image Credit & Copyright: André van der Hoeven

The 2016 Perseid meteor shower peaks on the morning of August 12.  The image above shows an animation of a Perseid from the 2015 shower.

Meteor showers occur when the left-over dust particles from a comet, a mashup of dust and ices, intersect our planet’s orbit.  As a comet passes near the sun, the ices vaporize and a trail of dust particles is left behind in the comet’s orbit.  This debris tracks around the sun in or near the host’s comet orbit.  If this orbit crosses the earth’s orbit, the dust particles enter the atmosphere.  The particles’ rapid speed, nearly 40 miles a second, causes friction with the atmosphere and the dust rapidly vaporizes in a flash of light as it streaks through the atmosphere: a shooting star or falling star or, simply, meteor.

Image Credit

A shower from a comet stream appears to emerge from a single spot in the sky, the radiant.  The meteor can appear anywhere in the sky.  The radiant occurs because of the perspective effect like the railroad tracks in the image above where the rails seem to emerge from the train tunnel.

The Perseids are named because their radiant is in the constellation Perseus.

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The chart above shows the radiant in Perseus along with the stars Capella and Aldebaran, and the star cluster the Pleiades.  Besides seeing meteors from the shower, other meteors not associated with the shower can be visible.  These sporadic meteors occur nearly randomly.  While Perseids can be seen anywhere in the sky, their pathway can be traced back to the radiant.  Sporadic meteors’ paths do not trace back to the shower’s radiant.

This year, some media outlets are reporting that 150 meteors per hour may be visible on the peak morning.  The Observer’s Handbook is predicting 90 per hour.  These numbers are rates for the entire sky in a very dark location. No single observer can see all these meteor in an hour.  A reasonable estimate for a single observer in a dark location is 15-25 meteors per hour. For a single observer near a city, the reasonable count is 5-15.  In a city, 1-5 meters per hour.

2016, August 6: Five Planets

This evening five planets appear in the west and southern sky, along with the moon as seen from the Chicago area.

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With a very good western horizon, Venus appeared low in the bright colors of twilight.  First found with binoculars, Venus was easy to see without optical aid.  As the sky darkened Mercury was visible through binoculars but not without them.  Jupiter was higher in the sky with the crescent moon farther south.

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Farther to the south, Mars and Saturn were easy to locate without optical help.

Look during the next few evenings as Mercury is beginning a rapid descent back into the sun’s glare.

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