07/06/2015- Ephemeris – Today we are at our greatest distance from the sun.

July 6, 2015 Leave a comment

Ephemeris for Monday, July 6th.  Today the Sun will be up for 15 hours and 26 minutes, setting at 9:30.   The Moon, 2 days before last quarter, will rise at 12:23 tomorrow morning and tomorrow the Sun will rise at 6:04.

This is the day the we are the farthest we can get from the Sun for the year.  The point in the Earth’s orbit that it occurs is called aphelion.  Earth is closest to the Sun in January at perihelion.  The actual distance difference between perihelion and aphelion is 3 million miles out of roughly 93 million miles.  So now we’re roughly 94 and a half million miles from the Sun or 152 million kilometers., and will swoop down to 91 and a half million miles(91.4) or 147 kilometers from the Sun in early January.  Because Earth’s northern and southern hemispheres have different ratios and placement of land versus ocean I’m not sure you could correlate seasonal differences of the hemispheres with the Earth’s distance from the Sun.  Anyway the approximate time we reach aphelion will be 3 p.m. EDT (19 hr UT).

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

Addendum

The orbits of the inner planets. (P)erihelion - (A)phelion

The orbits of the inner planets. (P)erihelion – (A)phelion

The above is a diagram from three years ago, so the planets other than the Earth will be in different positions today.  The date of aphelion and perihelion move around over a greater range of dates than the equinoxes and solstices.  I’m not sure why without researching it, but I suspect that the Moon has something to do with it.

07/03/2015 – Ephemeris – Astronomy in the Grand Traverse Region tonight

July 3, 2015 Leave a comment

Ephemeris for Friday, July 3rd.  Today the Sun will be up for 15 hours and 29 minutes, setting at 9:31.   The Moon, 2 days past full, will rise at 10:33 this evening and tomorrow the Sun will rise at 6:02.

Dr. David Penney will investigate the structure of the Milky Way at this evening’s meeting of the Grand Traverse Astronomical Society at 8 p.m. at Northwestern Michigan College’s Rogers Observatory.  The Milky Way is the band of light we see in the sky especially on summer and winter evenings.  But it is more than a band of dim stars, it is what we can see of the huge disk of maybe 200 billion stars with an embedded pin wheel structure.  Everyone is welcome.  Also at 9 p.m. there will be a star party at the observatory.  The astronomical objects of the evening will be the planets Venus, Jupiter and Saturn and the Moon later in the evening.  The observatory is located south of Traverse City on Birmley Road.

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

Addendum

Dr. Penney has a Ph.D. in Physiology and Biochemistry, and is pretty much retired spending his time between Michigan in the summer and northern Florida in the winter, where he is a member of several astronomy clubs.  He gives many talks there also.

07/02/2015 -Ephemeris – A belated preview of July’s skies

July 2, 2015 1 comment

Ephemeris for Thursday, July 2nd.  Today the Sun will be up for 15 hours and 30 minutes, setting at 9:31.   The Moon, 1 day past full, will rise at 9:48 this evening and tomorrow the Sun will rise at 6:02.

Lets preview July’s skies a day late.  Sorry, it’s been a busy week.. The sun, having reached its northern solstice, is beginning to slide southward again, at first imperceptibly, then with greater speed.  The daylight hours will decrease from 15 hours and 30 minutes Today to 14 hours 44 minutes at month’s end.  The daylight hours will be slightly shorter south of Interlochen, and slightly longer to the north.  The altitude of the sun at local noon, when the sun is due south will decrease from 68 degrees Now to 63 degrees at month’s end.  The sun will be a degree lower in the Straits area.  Despite the warmth, the earth will reach its greatest distance from the sun on Monday the 6th.  The range of the earth’s distance from the sun is 3 million out of 93 million miles.

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

Addendum

July Star Chart

Star Chart for July 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 11 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 midnight. EDT on July 1st, decreasing to 11:14 p.m. EDT on the 31st.

Morning astronomical twilight starts at 3:32 a.m. EDT on July 1st, and increasing to 4:42 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

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 Moon-Jupiter: 4.5° N means Jupiter will appear 4.5° north of the Moon.

 Date       Local   Event
             Time
Jul  01     We    02:48    Moon South Dec.: 18.4° S
     01     We        Venus: 42.4° E
     01     We    22:20    Full Moon
     05     Su    14:54    Moon Perigee: 367100 km
     06     Mo    08:59    Aphelion: 1.0167 AU
     07     Tu    20:07    Moon Descending Node
     08     We    16:24    Last Quarter
     12     Su    13:55    Moon-Aldebaran: 0.9° S
     14     Tu    00:24    Moon North Dec.: 18.4° N
     14     Tu    17:35    Venus-Regulus: 2.3° S
     15     We    21:24    New Moon
     18     Sa    13:34    Moon-Jupiter: 4.5° N
     18     Sa    21:06    Moon-Venus: 0.5° N
     21     Tu    07:02    Moon Apogee: 404800 km
     21     Tu    15:32    Moon Ascending Node
     23     Th    15:18    Mercury Superior Conjunction with the Sun
     24     Fr    00:04    First Quarter
     26     Su    04:43    Moon-Saturn: 2.4° S
     28     Tu    10:23    Delta Aquarid Meteor Shower: ZHR* = 20
     28     Tu    13:34    Moon South Dec.: 18.3° S
     31     Fr    06:43    Full Moon
Aug  01     Sa        Venus: 21.5° E

*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.

07/01/2015 – Ephemeris – Jupiter, Venus and Saturn grace our evening sky

July 1, 2015 Comments off

Ephemeris for Wednesday, July 1st.  Today the Sun will be up for 15 hours and 31 minutes, setting at 9:32.   The Moon, at full today, will rise at 8:58 this evening and tomorrow the Sun will rise at 6:01.

Lets take a look at the bright planets for this week.  Our brilliant evening star Venus and Jupiter are close together in the west by 9:45 p.m. They will set around 11:45 p.m..  Venus’ will slide down to the Sun faster and faster in the coming weeks leaving Jupiter behind for a while.  Venus will take a month and a half to slide past the Sun.  Jupiter though will take 2 months, 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 southeast in evening twilight.  It will pass due south at 10:53 p.m. and will set at 3:41 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

Evening Planets

The evening planets and the Moon at 10:30 p.m. July 1, 2015. Though their images overlap Jupiter is above right of Venus. Click on the image to enlarge. Created using Stellarium. 

Evening Planets apparent sizes

The evening planets and the Moon with their satellites to scale at 10:30 p.m. July 1, 2015. Created using Stellarium.

Mercury is officially in the morning sky now, but it is not a favorable appearance for northern hemisphere observers.

06/30/2015 – Ephemeris – Tonight’s close conjunction of Jupiter and Venus will be visible in the west after sunset

June 30, 2015 Comments off

Ephemeris for Tuesday, June 30th.  Today the Sun will be up for 15 hours and 31 minutes, setting at 9:32.   The Moon, 1 day before full, will set at 5:49 tomorrow morning and tomorrow the Sun will rise at 6:00.

Tonight the planets Venus and Jupiter will appear at their closest in the western sky after sunset.  Dimmer Jupiter will appear just above Venus by 20 minutes of arc or two-thirds of the width of the Moon.  They can both be seen in the same telescope field using low power.  It’s interesting that Jupiter, is over 11 times the diameter of Venus, but because Venus is so much closer to us, it now appears to be the same size as Jupiter, and it will continue to grow.  It’s 48 million miles away and closing to 27 million on August 15th when it passes between the Earth and the Sun.  Astrologers think a conjunction like this means something, while astronomers like me see two bright planets which happen to be beautifully aligned along our line of sight.

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

Addendum

Jupiter-Venus animation

Jupiter-Venus approach animation June 11 to July 1, 2015 at 10:30 p.m. Created using Stellarium and GIMP. Click on image to enlarge.

Telescopic 2015

A telescopic view of what we expect the positions of Jupiter and Venus at 10:30 p.m. EDT June 30, 2015 (2:20 UT July 1, 2015). Created using Stellarium.

06/29/2015 – Ephemeris – Did tomorrow’s conjunction between Venus and Jupiter happen before?

June 29, 2015 Comments off

Ephemeris for Monday, June 29th.  Today the Sun will be up for 15 hours and 32 minutes, setting at 9:32.   The Moon, 2 days before full, will set at 4:56 tomorrow morning and tomorrow the Sun will rise at 6:00.

Tonight the planet Jupiter will be a bit more than the width of the Moon away from Venus.  Tomorrow that distance will be cut in half as Jupiter will pass directly above Venus.  This is a second of two conjunctions that are a near repeat of two conjunctions that some, including myself have speculated as being what the Magi reported as the Star of Bethlehem in 3 and 2 BC.  On August 12th 3 BC in the predawn sky Jupiter and Venus were a third of a moon width apart,  Then on June 17th 2 BC they were in conjunction again but even closer .  Last year we had a close conjunction of the two on August, 18th and the two will be in conjunction, and again tomorrow.  Neither are as close as they were in 3 and 2 BC.

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

Addendum

Tonight

Jupiter and Venus at 10:30 tonight June 29, 2015, one day before their conjunction. Created using Stellarium.

Orbits of Venus and Jupiter now

The orbits of Venus and Jupiter for the conjunction of June 30, 2015. The bright star to the upper left is Regulus.  Created using Stellarium.

Telescopic 2015

A telescopic view of what we expect the positions of Jupiter and Venus at 10:30 p.m. EDT June 30, 2015 (2:20 UT July 1, 2015). Created using Stellarium.

Orbits of Venus and Jupiter 2 BC

The orbits of Venus and Jupiter for the conjunction of June 17, 2 BC. The bright star to the lower right is Regulus.  Created using Stellarium.

Telescopic Jupiter and Venus 8/12/3 BC.

Venus appeared among Jupiter’s moons on August 12, 3 BC. Of course no one had a telescope back then. Created using Stellarium.

I’ve written about the Jupiter-Venus conjunctions of 3 and 2 BC.  You can see it here from my Ephemeris website..

06/26/2015 -Ephemeris – The latest sunset of the year

June 26, 2015 Comments off

Ephemeris for Friday, June 26th.  Today the Sun will be up for 15 hours and 33 minutes, setting at 9:32.   The Moon, 2 days past first quarter, will set at 2:57 tomorrow morning and tomorrow the Sun will rise at 5:59.

This evening we will experience the latest sunset of the year.  The sun has been setting within the same minute for a few days now.  Now the Sun will begin to set earlier and earlier,  at first imperceptibly, but soon with greater speed.  By the middle of August the Sun will set 45 minutes earlier.  Just in time to enjoy the summer Milky Way at a semi-decent hour.  The shorter days, or actually daylight hours, and the diminishing altitude of the Sun at noon will cause a decrease in the heat we receive from the Sun.  Still, right now we’re still warming up.  However there is a tipping point around mid to late July, when we will not get enough heat to keep getting warmer and we’ll start to cool.

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

Addendum

Average Monthly Climate Chart

Traverse City Climate Chart. The hottest day is around July 15, and coldest day is around January 20. Credit: http://www.usclimatedata.com

www.usclimatedata.com has monthly and daily average data for many locations in the United States.  They have code to embed this chart on your website.  However it didn’t embed properly in the blog, so I took a screen shot.

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