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Posts Tagged ‘Aphelion’

07/03/2017 – Ephemeris – The Earth is farthest from the Sun today

July 3, 2017 1 comment

Ephemeris for Monday, July 3rd. Today the Sun will be up for 15 hours and 28 minutes, setting at 9:30, and it will rise tomorrow at 6:03. The Moon, 3 days past first quarter, will set at 3:13 tomorrow morning.

At 8:59 tonight the Earth will pass a point in its orbit of the sun called aphelion, the farthest point from the sun of 94.5 million miles (152 million km). The whole Earth gets something like 6% less heat from the Sun than early January when the Sun is closest. So why is it summer now? The difference in distance from the sun pales as a cause of the seasons next to the tilt of the earth’s axis. Six months ago, because the sun was up for a shorter period each day, and didn’t rise very high in the sky, the sun gave us in northern Michigan something like 70% less heat than it does now. The real effect of aphelion coming in summer is that it makes summer the longest season at 94 days. This is because the farther the Earth is from the Sun, the slower it travels. Hey, it’s summer – take the hint and slow down and enjoy the season.

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

 

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06/20/2016 – Ephemeris – Summer will start later today

June 20, 2016 Comments off

Ephemeris for Monday, June 20th.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57.  The Moon, at full today, will rise at 9:32 this evening.

Well, this is it, the last 12 hours of spring.  Summer will begin at 6:35 this evening.  In the southern hemisphere the season of winter will begin, and the south pole of the Earth will begin* is in the middle of its six months of darkness.  The north above 66 ½ degrees north latitude is the land of the midnight Sun.  Over summer that line will creep northward as the Sun heads southward.  The seasons are caused by the tilt of the Earth’s axis, not by the Earth’s change in distance from the Sun.  In fact we are approaching our farthest distance from the Sun, of about 94.5 million miles (152 million km) on the fourth of July called aphelion.  The greater than normal distance makes summer the longest season at 93.7 days, winter being the shortest at 89 days.

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

* Thanks to Jeff Silagy for spotting the error.

Addendum

Summer Solstice

The sun’s daily path through the sky from horizon to horizon on the first day of summer, the summer solstice. Credit My LookingUp program.

Earth at summer solstice

Earth from the DSCOVR satellite at the June solstice 2015. Credit NOAA.

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

July 6, 2015 Comments off

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.

07/02/2015 -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.

07/03/2014 – Ephemeris – Today the Earth is its farthest from the Sun for this year

July 3, 2014 Comments off

Thursday, July 3rd.  Today the sun will be up for 15 hours and 28 minutes, setting at 9:30.   The moon, 2 days before first quarter, will set at 12:35 tomorrow morning.  Tomorrow the sun will rise at 6:02.

Later today the Earth will pass a point in its orbit called aphelion.  This is the point where the Earth is its farthest from the Sun.  Astronomers measure it in terms of the astronomical units AU), the mean distance between the Earth and the Sun.  In astronomical units the Earth will be 1.01668 AU from the Sun at 6:59 p.m. (22:59 UT).  Converted to miles it is 94.51 million miles (152.1 million km).  The 1.7 percent farther distance from the Sun doesn’t really show up as making a difference in temperature.  It is swamped by the greater effect of the Earth’s axial tilt currently giving us our summer season.  The one thing about aphelion in summer gives us is a longer summer, than winter.  The Earth travels slightly slower when farther from the Sun than when closer to it, so summer is the longest season at 94 days.

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

Note that the chart is from 2012.  The date of aphelion and perihelion varies by a day or two each year.  Mars and Mercury have the most eccentric orbits.

Categories: Earth, Ephemeris Program, Events Tags:

07/05/2013 – Ephemeris – Earth at aphelion and astronomy tonight

July 5, 2013 Comments off

Ephemeris for Friday, July 5th.  Today the sun will be up for 15 hours and 26 minutes, setting at 9:30.   The moon, 3 days before new, will rise at 4:52 tomorrow morning.  Tomorrow the sun will rise at 6:04.

The earth is as far as it will get from the sun for the year today at  94.5 million miles.  Speaking of the sun, the monthly meeting of the Grand Traverse Astronomical Society at 8 p.m. at Northwestern Michigan College’s Rogers Observatory tonight will host local landscape architect Dean Conners an expert on sundials.  He created the sundial in the Children’s Garden behind the District Library. who will talk about some interesting sundials.  After the meeting at 9 p.m. there will be a star party at the observatory with the planets Venus and Saturn plus some of the bright wonders of the summer sky, like the Ring Nebula, The Great Hercules Globular Star Cluster if it’s clear.  There’s other activities if it’s cloudy.

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

 

07/01/2013 – Ephemeris – July preview

July 1, 2013 Comments off

Ephemeris for Monday, July 1st.  Today the sun will be up for 15 hours and 29 minutes, setting at 9:31.   The moon, 1 day past last quarter, will rise at 2:11 tomorrow morning.  Tomorrow the sun will rise at 6:01.

Lets preview July’s skies. 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 29 minutes today to 14 hours 40 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 tomorrow 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 Friday.  The planets Venus and Saturn will be our evening planets this month.

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

Addendum

Stars and Planets

The stars and planets, specifically for July 15, 2013 at 11 p.m.

The constellation abbreviations, names and bright star names are found here.

  • The arrow from the pointer stars of the Big Dipper to Polaris the North Star, near the north celestial pole.
  • Follow the arc of the handle of the Big Dipper to Arcturus.
  • A Leaky Dipper drips on Leo
  • Follow the spike to Spica.
  • The Summer Triangle (in red)