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06/22/2020- Ephemeris – Summer has begun

June 22, 2020 Comments off

This is Ephemeris for Monday, June 22nd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 1 day past new, will set at 11:04 this evening.

On Friday’s program I was way too busy with the summer solstice and the annular eclipse in Asia to properly give summer its due, so here goes. Last Saturday the northern end of the Earth’s axis was tilted toward the Sun to its maximum extent, giving the northern hemisphere its most direct sunlight, and the longest daylight hours. North of the arctic circle of 66 ½ degrees latitude got 24 hours of daylight, and the north pole midday in its six months of continuous sunlight. At the south pole it’s literally midnight of its six months night. The northern hemisphere got its greatest amount of heat from the Sun that day, however this part of the Earth is still warming up, so our hottest days average in late July when the shortening daylight hours and the lowering of the Sun in the south can’t maintain the heat anymore and we begin to cool.

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

Addendum

Earth's position at the solstices and equinoxes

Earth’s position at the solstices and equinoxes. This is an not to scale oblique look at the Earth’s orbit, which is nearly circular. The Earth is actually farthest from the Sun on July 4th. Click on the image to enlarge. Credit: ESO (European Southern Observatory which explains the captions in German and English.

Solstices

Comparing the sun’s path at the summer and winter solstices. This is a stereographic representation of the whole sky which distorts the sky and magnifies the size of the sun’s path near the horizon.

06/19/2020 – Ephemeris – Summer arrives tomorrow with an eclipse of the Sun the next day

June 19, 2020 Comments off

This is Ephemeris for Friday, June 19th. 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, 2 days before new, will rise at 5:25 tomorrow morning.

Tomorrow afternoon at 5:43 pm summer will begin, as the Sun reaches its greatest northerly excursion, right over the tropic of Cancer, 23 ½ degrees north latitude on the Earth’s surface. It’s called the summer solstice for those of us north of the equator. Early Sunday morning there will be an annular eclipse of the Sun. We won’t see it in the United States, however it will be visible for parts of Africa and southern Asia. The Moon will be too far away to completely cover the face of the Sun leaving a ring or annulus at maximum eclipse, a so-called Ring of Fire. It is the second of a triad of eclipses this eclipse season. Two weeks ago there was a slight eclipse of the Moon and two weeks from now another slight eclipse of the Moon to finish the season.

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

Addenda

Annular Eclipse

Eclipse Map for june 21, 2020

Areas of the Earth where the solar eclipse of June 21, 2020 will be visible. The central double red line delineates the path of annularity. Click on the image to see the original chart. Credit NASA GSFC, Fred Espenak.

Annular eclipse May 10 1994

My photograph of the Annular eclipse May 10 1994 taken east of Toledo, Ohio, May 10, 1994.

Summer Solstice

Earth and local area near summer solstice

Earth and magnified local area near summer solstice. Image taken near local noon June 17, 2020. Credit NOAA DSCOVR satellite orbiting the Sun-Earth L1 point 994,970 miles (1,601,432 kilometers) sunward from the Earth. For once it’s clear enough to see the mitten of the Lower Peninsula of Michigan.

The Sun's path on the summer solstice

The Sun’s path through the sky on the summer solstice day from Traverse City, MI. Created using my LookingUp program..

06/21/2018 – Ephemeris – Yay, summer is here!

June 21, 2018 Comments off

Ephemeris for Thursday, June 21st. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 1 day past first quarter, will set at 2:57 tomorrow morning.

Welcome to summer! It began at 6:07 this morning. If you remember back to winter and the beautiful constellation of Orion. Some folks could trace the club he was holding over his head off the red star Betelgeuse. The Sun now appears above that. If you remember Gemini the twins, well the Sun is off Castor’s big toe. That’s all pretty high in the sky and giving us 15 hours and 34 minutes of daylight. That’s why summer’s so hot. This despite the fact that in two weeks we will be the farthest we get from the Sun all year. The 3 million mile difference in the Sun’s annual distance is peanuts compared to the seasonal fluctuations caused by the tilt of the Earth’s axis.

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

Addendum

The Sun with its position with the stars at the summer solstice

The Sun with its position with the stars at the summer solstice, June 2018. Click on the image to enlarge. Created using Stellarium and GIMP.

Summer Solstice

The sun’s daily path through the sky from horizon to horizon on the first day of summer, the summer solstice. Grid lines are 15° apart. The Sun os plotted at 15 minute intervals. Credit: My LookingUp program.

 

06/20/2017 – Ephemeris – Summer will begin overnight tonight

June 20, 2017 1 comment

Ephemeris for Tuesday, June 20th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, half way from last quarter to new, will rise at 4:11 tomorrow morning.

Summer will begin overnight at 12:25 a.m. (4:25 UT June 21, 2017) The sun will at its highest at noon today and tomorrow, well at local solar noon that is, which is 1:44 p.m. in the Interlochen Traverse City area. At that time the Sun will reach an altitude or angle above the southern horizon of nearly 69 degrees. If you want to get an idea of the difference between that and the Sun at the winter solstice, check out Saturn tonight. It is almost to the point in the sky where the Sun was at the winter solstice. Notice how low it is in the sky, and how few hours it is up. The cause is the tilt of the earth’s axis of 23 and a half degrees. It gives us a 47 degree span of altitudes of the sun over the year. It is not the sun’s distance that causes seasons, as we’ll see next month.

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

Addendum

The Sun's path on the summer solstice

The Sun’s path through the sky on the summer solstice day from Traverse City, MI. Created using my LookingUp program.

Earth at summer solstice

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

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.

06/14/2016 – Ephemeris – Tomorrow is the earliest sunrise of the year

June 14, 2016 Comments off

Ephemeris for Flag Day, Tuesday, June 14th.  Today the Sun will be up for 15 hours and 33 minutes, setting at 9:30, and it will rise tomorrow at 5:56.  The Moon, 2 days past first quarter, will set at 3:22 tomorrow morning.

Tomorrow morning’s sunrise is the earliest sunrise of the year.  Sunrises of the next few days will stay within the same minute.  The bottoming out of the earliest sunrise is a slow affair, but the advance of the sunrise times will accelerate in the coming weeks.  We are still nearly two weeks from the latest sunset on the 26th.  That means that the summer solstice, the first day of summer is near, on the 20th.  The reason for the uneven sunrise and sunset peaks is due to a combination of the Earth’s axial tilt and the Earth’s elliptical orbit which is too complicated to explain here.   These times of sunrise and sunset are for the Traverse City/Interlochen area.  I have a link for other locations and times on bobmoler.wordpress.com.

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

Addendum

Here is the link to the calendar page on my Ephemeris website.

12/15/2015 – Ephemeris – Procyon the star that’s “Before the dog”

December 15, 2015 Comments off

Ephemeris for Tuesday, December 15th.  The Sun will rise at 8:13.  It’ll be up for 8 hours and 49 minutes, setting at 5:02.   The Moon, 3 days before first quarter, will set at 9:48 this evening.

Visible low in the east at 9:30 p.m. appears the star Procyon to its lower left is Sirius the brightest night-time star.  Procyon is the bright star in the constellation Canis Minor, or lesser dog.  I can find only one other star in Canis Minor.  Perhaps it’s a hot dog.  If Sirius, in Canis major is the Dog Star then Procyon should be the Little Dog Star.  However Procyon is an interesting name.  It means “Before the dog”, which is an allusion to the fact that Procyon, though east of Sirius actually rises before it.  This is due to Procyon’s more northerly position.  This effect doesn’t work south of the equator, however.  Sirius will rise at about 9 tonight.  Procyon is a star much like Sirius but is 32% farther away.  It’s 11.4 to Sirius’ 8.6 light years away.

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

Addendum

Procyon, Sirius and the stars of winter. Created using Stellarium

Procyon, Sirius and the stars of winter. Created using Stellarium

In the above chart, beside the constellation lines, we have the grid of right ascension, from lower left to upper right; and declination, from upper left to lower right.  right ascension lines are like longitude on the Earth, while declination lines are latitude lines.  They are tipped because I don’t live at either the equator or one of the poles.  As the Earth rotates the Sun, stars and planets slide westward in the direction of the declination lines.  Note that Sirius is closer to the horizon than Procyon.  Also that Sirius is west of the 7 hour right ascension line. (Take my word for it.)  Procyon is  east of that line, thus Sirius is west of Procyon.

Other cool things can be seen in the chart.  Note the declination line that touches the horizon at the east compass point and runs just above Orion’s belt.  It is 0º declination, or the celestial equator.  It extends to the west compass point on the western horizon.  The Sun on the equinoxes will rise due east and set due west.  The 6 hour right ascension line runs past Betelgeuse in Orion.  At 23½º north declination, near Castor’s big toe in Gemini is where the Sun appears on the first day of summer, the summer solstice.

P.S. It was cloudy and rainy the last two days.  Didn’t see a Geminid meteor again this year, keeping my record intact.

06/19/2015 – Ephemeris – Two events this weekend: one local, one global

June 19, 2015 Comments off

Ephemeris for Friday, June 19th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31. The Moon, 3 days past new, will set at 11:34 this evening. Tomorrow the Sun will rise at 5:56.

There’s a couple of astronomical events coming up this weekend. On Saturday there will be another Sun ‘n Star Party at the Sleeping Bear Dunes National Lakeshore if weather cooperates. This time the telescopes will be set up at the Pierce Stocking Scenic Drive, Stop 3, the Dunes Overlook from 4 to 6 p.m. and from 9 to 11 p.m. The best place to park is Picnic Mountain, just before the Dunes Overlook. On Sunday a truly global event, the Summer solstice will occur at 12:38 p.m. (16:38 UT), when the Sun will reach its farthest north signaling the start of summer in the northern hemisphere. For folks south of the equator it will be the winter solstice signaling the start of winter for them.

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

Addendum

Summer Solstice Sun's Path

The Sun’s apparent path in the sky on the summer solstice. The cyan circle is the horizon and the Sun is plotted every 15 minutes throughout the day. Created by Bob Moler using LookingUp. This is a slide from his school program on the cause of the seasons.

06/16/2014 – Ephemeris – Dates of the earliest sunrise and latest sunset

June 16, 2014 Comments off

Ephemeris for Monday, June 16th.  Today the sun will be up for 15 hours and 33 minutes, setting at 9:29.   The moon, half way from full to last quarter, will rise at 12:11 tomorrow morning.  Tomorrow the sun will rise at 5:56.

Yesterday saw the earliest sunrise for the year.  My sunrise times will start to show a change on Thursday.  The day-to-day change in sunrise times are now a few seconds.  The summer solstice, or longest day will be this Saturday, and the latest sunset won’t occur until next week Thursday.  The reason these dates don’t coincide has to do with the tilt of the earth’s axis and the earth’s slightly elliptical path around the sun.  Actually the disparity between these dates is more pronounced at the winter solstice when the Earth is closer to the sun and moving faster.  Yup, the sun is farther away now than it was in December.  Actually we’re moving slower now, so summer lasts a few days longer than winter.

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

 

02/18/2014 – Ephemeris – Gemini and the summer solstice

February 18, 2014 Comments off

Ephemeris for Tuesday, February 18th.  The sun will rise at 7:38.  It’ll be up for 10 hours and 37 minutes, setting at 6:15.   The moon, half way from full to last quarter, will rise at 10:19 this evening.

The constellation Gemini lies above and left of Orion in the southern evening sky.  Jupiter is now seen against its stars.  Gemini is called the twins and its head stars at the upper left of the constellation are Castor and Pollux.  Pollux is to the lower left of Castor.  Stick figures of the lads can be seen extending to the lower right of these stars.  Currently the place in the sky where the sun is on the winter solstice is just to the right of Castor’s big toe.  So it would seem that the sun is entering Gemini on the first day of summer, not Cancer as the astrologers would tell you.  That solstice point is moving westward at one degree every 71.6 years, a motion called precession.  I checked two astronomy programs and that point has now moved into Taurus the bull.

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

Addendum

Gemini and the summer solstice

The constellation Gemini and the summer solstice point in the sky. Created using Stellarium.

The summer solstice point in the sky is the intersection of the ecliptic, the suns path in the sky and the 6 hour line of right ascension which is like longitude on the earth.  The other blue lines are lines are lines of declination which is like latitude in the sky.  Note also that the summer solstice point is the point on the ecliptic closest to the blue declination line which is the 25º north declination line.  It’s at approximately 23½º north declination, right over the earth’s 23½º north latitude line also known as the Tropic of Cancer.

Back a couple of thousand of years ago the sun was entering the constellation of Cancer, off our image to the left, on the first day of summer.  Since then the summer solstice point has moved westward against the stars at one degree every 71.6 years.  This is due to what is called general precession, of the slow wobble of the earth’s axis caused by the  pull of the Moon and Sun on the Earth’s equatorial bulge.  This torques the earth and causes the 26,000 year wobble, like a spinning top.  Since back then the solstice point passed all the way across Gemini and in 1989 entered the territory of Taurus.