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Archive for June, 2015

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.

06/25/2015 – Ephemeris – Lunar seas and highlands tell the story of the Moon’s history

June 25, 2015 Comments off

Ephemeris for Thursday, June 25th.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32.   The Moon, 1 day past first quarter, will set at 2:26 tomorrow morning and tomorrow the Sun will rise at 5:58.

Tuesday I talked about the brightness variation on the Moon, the bright and ancient highlands and the darker areas called seas, but a large asteroid impact areas that welled up magma from the moon’s interior erasing prior craters.  The dark seas were created after most cratering had ended, or they’d be heavily cratered too.  They seem to have occurred about 4 billion years ago, about 500 million years after the Moon formed.  This appeared to be a period when the giant planets came closer to the Sun than they are now, before retreating again.  This period is called the late heavy bombardment.  Not all astronomers give it credence, but it bears out what we see in planetary systems around other stars.

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

Addendum

The Moon tonight

The Moon tonight with pointers to seas near the crater Copernicus and the highlands near the crater Tycho. 10:30 p.m. June 25, 2015. Created using Virtual Moon Atlas.

Copernicus area

The Lunar seas near the crater Copernicus showing the smooth surface with relatively few craters. Credit: Virtual Moon Atlas with the texture from NASA’s Lunar Reconnaissance Orbiter. The lunar phase was omitted.

Lunar highlands

The Lunar highlands near the crater Tycho showing a surface saturated with craters. Credit: Virtual Moon Atlas with the texture from NASA’s Lunar Reconnaissance Orbiter. The lunar phase was omitted. Both images are shown to the same scale.

06/24/2015 – Ephemeris – Jupiter and Venus inch closer while Saturn keeps its distance

June 24, 2015 Comments off

Ephemeris for Wednesday, June 24th.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32.   The Moon, at first quarter today, will set at 1:58 tomorrow morning and tomorrow the Sun will rise at 5:58.

Lets take a look at the bright planets for this week.  Our brilliant evening star Venus is in the west by 9:45 p.m. It will set around midnight.  Venus’ will slide down to the Sun faster and faster in the coming weeks.  It will take a bit less than 2 months.  Jupiter will appear western sky to the left of and slightly above Venus at about 10 p.m.  It will set at 12:09 a.m.  It seems to approach Venus, and now appears about 3 and a half degrees away.  That’s about three finger widths held at arm’s length.  They will cross paths in 6 days, on the 30th.  Saturn is in the southeast in evening twilight.  It will pass due south at 11:22 p.m. and will set at 4:10 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

The Evening planets and the Moon

Jupiter and Venus converge in the west while the Moon and Saturn look on. 10:30 p.m., June 24, 2015. Created using Stellarium.  Click to enlarge.

Moon

Closeup of the Moon at 10:30 p.m. June 24, 2015. Created using Stellarium.

Apparent sizes of Planets and Moon to scale

The evening planets and the Moon using the same magnification at 10:30 p.m., June 24, 2015. Created using Cartes du Ciel (Sky Charts). Click on image to enlarge.

Note that over the last few Wednesdays that I’ve portrayed the planets at the same scale that Venus has been getting larger with respect to Jupiter as it approaches the Earth and Jupiter moves away.

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.

 

06/23/2015 – Ephemeris – What can you tell about the appearance of the Moon to the naked eye?

June 23, 2015 Comments off

Ephemeris for Tuesday, June 23rd.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32.   The Moon, 1 day before first quarter, will set at 1:31 tomorrow morning and tomorrow the Sun will rise at 5:57.

The Moon is at nearly half phase or first quarter.  The unaided eye can see that the Moon has darker and lighter areas.  The Greeks, who thought the objects in the heavens were perfect thought that the Moon was a silvery sphere.  They never quite figured out why the moon had this mottled appearance.  So why are the bright parts different from the darker parts?  The bright parts are called the highlands and are the oldest part of the Moon’s surface.  It’s saturated with craters from impacts since the Moon formed.  The dark areas are roughly circular, and are really vast craters that penetrated through the Moon’s crust to bring up molten lava that repaved the surface of the Moon some 500 million years after it formed.

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

Addendum

The Moon

The Moon tonight (June 23, 2015). Look at the difference in the surface albedo (reflectance) between the light and dark areas and wonder about their origins. Created using Virtual Moon Atlas.

There’s a severe geomagnetic storm in progress at 7 p.m. EDT (23:00 UT) June 22, 2015

June 22, 2015 Comments off

There’s a good chance for auroras (northern/southern lights) tonight at moderate latitudes.  In Michigan: we’re under clouds now.  Skies may clear by midnight for the west side of the lower peninsula of Michigan according to Anttilla Danko’s Clear Sky Charts, such as this for the Lanphier Observatory in Glen Arbor.  Also check spaceweather.com

Categories: Uncategorized

06/22/2015 – Ephemeris – The summer full moon and the winter Sun trade places

June 22, 2015 Comments off

Ephemeris for Monday, June 22nd.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32.   The Moon, 2 days before first quarter, will set at 1:04 tomorrow morning.  Tomorrow the Sun will rise at 5:57.

Summer’s here, and it’s a few days before the latest sunset and latest end of twilight.  It might be instructive to check out the height of the moon over the next two weeks or so.  The moon is heading south in front of the Sun.  The Sun besides its apparent westward motion during the day caused by the Earth’s rotation also moves about twice its diameter each day eastward against the stars caused by the earth’s motion in its orbit of the Sun.  Around July 1st, the moon will be about where the Sun will be next winter solstice, 4 days before Christmas.  Actually it will be about 8 moon widths above where the Sun will be because its orbit is tilted a bit to the Earth’s.  But it will serve as an illustration of the seasonal difference.

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

Addendum

Summer full moon

The full moon nearest the summer solstice. The full moon appears near where the sun would appear low in the south at the winter solstice. The bottom red line is the ecliptic, the path of the Sun. Created using Stellarium.

Moon near the winter solstice

The full moon nearest the winter solstice. The full moon appears near where the sun would appear high in the south at the summer solstice. The top red line is the ecliptic, the path of the Sun. Created using Stellarium.

The Moon’s orbit has a slight tilt of a bit more than 5 degrees from the ecliptic, or plane of the Earth’s orbit of the sun.  The crossing point is called a node.  In the bottom image the node near the western horizon is called the descending node due to the fact that the Moon is heading south of the ecliptic.  When the Sun and Moon are near the same node the Moon will be new and we have a chance for a solar eclipse.  When at opposite nodes, a lunar eclipse.  The nodes slowly slide westward slowly one revolution in about 18.6 years, which causes eclipse seasons, about 6 months apart to occur a bit earlier each year.

Categories: Concepts, Seasons, The Moon Tags: , , ,

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.

06/18/2015 – Ephemeris – 26 days to Pluto!

June 18, 2015 Comments off

Ephemeris for Thursday, June 18th.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31.   The Moon, 2 days past new, will set at 10:57 this evening.  Tomorrow the Sun will rise at 5:56.

I hope everyone’s been following the progress of the New Horizons spacecraft as it nears the Pluto system.  It will reach and pass through the Pluto system on July 14th, only 26 days from now after a journey of 9 years. Now, Pluto is more than a dot in the probe’s cameras, which are used to look for possible hazardous rings of debris, more moons and for navigational purposes.  New Horizons is aimed for a window less than a hundred miles on a side, and a few minutes in time.  All its moves to study Pluto and its moons have been pre-programmed in and actually tested two years ago to make sure everything works.  We will not hear from the spacecraft on encounter day, it will be too busy.

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

Addendum

New Horizons

Artist conception of the New Horizons spacecraft at Pluto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

New Horizon's trajectory

New Horizon’s trajectory through the solar system. Credit: NASA/APL.

Encounter Timeline

New Horizons Encounter Timeline. Credit: NASA/JHAPL.

New Horizons at closest approach to Pluto

New Horizons at closest approach to Pluto. Credit: NASA/JHAPL.