05/05/2016 – Ephemeris – Previewing Monday’s transit of Mercury

Ephemeris for Thursday, May 5th.  The Sun rises at 6:26.  It’ll be up for 14 hours and 26 minutes, setting at 8:53.   The Moon, 1 day before new, will rise at 6:38 tomorrow morning.

Next Monday, the 9th, the tiny planet Mercury will be seen to cross that face of the Sun.  Astronomers call such an event a transit.  The last time a planet crossed the face of it Sun, it was Venus on June 5th, 2012, almost 4 years ago.  Very few, who were alive in 2012 will be around to see the next transit of Venus in 2117.  Transits of Mercury are more frequent.  Mercury will cross the face of the Sun from 7:12 a.m. to 2:42 p.m. on Monday.  Mercury is too small to see with eclipse filters or with the naked eye.  The latter could cause blindness.  Only telescopes with solar filters that fit over the front of the telescope are safe to use.  Mercury will be a tiny black dot, smaller than most sunspots.  Tomorrow I’ll have information about where to go to see it.

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

Addendum

Transit Map

Transit visibility map with added captions to make it more readable. Credit United States Naval Observatory, The Astronomical Almanac Online! 2016

rack of the Transit of Mercury

The track of Mercury across the face of the Sun. Mercury will travel from upper left to lower right. Mercury will not be visible until it impinges upon the disk of the Sun. Credit IOTA’s program Occult4.

From IOTA’s Occult4 program

Transit of Mercury on 2016 May 9 (TT)
   {'+' => next day; '-' => previous day }
                                           Overhead at
     Geocentric Event      UTC         P.A.  Long  Lat
                         h  m  s       o      o    o 

[1]  Exterior Ingress   11 12 16     83.1     11   17
[2]  Minimum Separation 14 57 38             -45   18
[3]  Exterior Egress    18 42 23    224.4   -102   18

Minimum sepn 318.5";  Radii - Sun 950.4", Mercury 6.0"
delta T =  68.2 secs,  Ephemeris = DE0

Note:  These timings are geocentric.  Occult4 has timings for various cities of the world.  Occult4.0.2 can be downloaded here.  They can vary by several minutes for different cities due to parallax.

05/04/2016 – Ephemeris – There are three bright planets out by midnight

Ephemeris for Wednesday, May 4th.  The Sun rises at 6:27.  It’ll be up for 14 hours and 24 minutes, setting at 8:52.   The Moon, 2 days before new, will rise at 5:59 tomorrow morning.

Let’s see what the bright naked eye planets are up to.  Mercury is too close to the Sun to be seen.  However next Monday it will be so close to the Sun that we’ll see it cross the Sun’s face.  Jupiter is in the south in the early evening, and will pass due south at 9:49 p.m., and will set at 4:23 a.m.  It’s below the stars of Leo this year.  Binoculars can make out some of Jupiter’s moons, but a telescope is required to see all four bright moons and Jupiter’s cloud features.  Mars will rise at 10:33 p.m. in the east-southeast.  It’s still above its look-a-like star Antares, whose name means Rival of Mars.  Mars is getting closer to the Earth now, only 52.2 million miles.  5 and a half million miles to go.  Saturn will rise at 11:06 p.m. in the east-southeast.  It’s just left of Mars.

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

Addendum

Planets at midnight

Jupiter, Mars and Saturn at midnight 12:00 a.m. May 5, 2016. Created using Stellarium.

Jupiter and moons

Jupiter and its moons as they might be seen through a telescope at 12 midnight May 5, 2016. It’s 40.3″ in diameter. Created using Cartes du Ciel (Sky Charts).

Mars through a large telescope

Mars as it might be seen in a large telescope with high power at midnight May 5, 2016. Mars apparent diameter is 16.7″. The central meridian will be 26.77 degrees. Syrtis Major is the large feature in the north near the polar cap. Created using Cartes du Ciel (Sky Charts).

Saturn and its moons

Saturn and its moons at midnight May 5, 2016. The apparent diameter of the planet will be 18.2″. The rings span 42.4″, a bit larger than the apparent diameter of Jupiter. Created using Cartes du Ciel (Sky Charts).

Sunset to sunrise on a single night

Planets at Sunrise and Sunset of a single night starting with sunset on the right on May 4, 2016. The night ends on the left with sunrise on May 5. I’ve also plotted the Eta Aquariid meteor shower radiant. If using Firefox right-click on the image and select View Image to enlarge the image. That goes for all the large images.

Categories: Ephemeris Program, Planets

05/03/2016 – Ephemeris – Halley’s Comet is back… In little bitty pieces

Ephemeris for Tuesday, May 3rd.  The Sun rises at 6:29.  It’ll be up for 14 hours and 21 minutes, setting at 8:50.   The Moon, 3 days before new, will rise at 5:23 tomorrow morning.

There’s a meteor shower happening this week that’s  a tough one for observers as far north as we are.  It’s the Eta Aquariids:  seeming to come from the Water Jar asterism of the constellation Aquarius the water bearer.  It will reach peak on Thursday the 5th, however the radiant point rises around 3:30 a.m., and twilight starts an hour and a half later.  The radiant is also low in the southeastern part of the sky.  The meteors are fast-moving and many of them are bright.  They are bits shed by Halley’s Comet and left in its orbit.  The Earth passes close to Halley’s orbit twice a year:  In late October as the particles come in from the outer solar system, and again in early May as they head back out again.  We’ll see souvenirs of Halley’s Comet before it returns in 2061.

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

Addendum

Eta Aquarid radiant

The Eta Aquarid radiant at the peak of the shower. The radiant moves slowly to the east with time. Credit: Bob Moler’s LookingUp program.

This meteor shower is low for us in the Northern Hemisphere, but it will be great for those Down Under.  The Moon is even cooperating this year, by getting out of the way.  The active dates for the shower are April 19th to May 28th. The velocity of the meteoroids that strike the atmosphere is 66 km/s.  Halley’s Comet, and thus its debris is traveling in a retrograde orbit, going the wrong way in a one way solar system, which is why the speed of the particles is so high.

04/29/2016 – Ephemeris – Let’s preview the merry skies of May

April 29, 2016 Comments off

Ephemeris for Arbor Day, Friday, April 29th.  The Sun rises at 6:34.  It’ll be up for 14 hours and 10 minutes, setting at 8:45.   The Moon, at last quarter today, will rise at 3:01 tomorrow morning.

Sunday starts the month when the promise of spring is finally fulfilled.  Daylight hours in the Interlochen/Traverse City area will increase from 14 hours and 16 minutes Sunday to 15 hours 20 minutes on the 31st.  The altitude, or angle, of the Sun above the southern horizon at local noon will ascend from 60 degrees Sunday to 67 degrees at month’s end.  The altitude of the sun in the Straits area will be a degree lower than that but your daylight will be a few minutes longer.   The big event of May will be the transit of the tiny planet Mercury across the face of the Sun on May 9th.  I’ll have more on that next week.  Also Mars will be in opposition from the Sun on the 22nd which due to its elliptical orbit will actually be closest to us 8 days later on the 30th at 46.779 million miles (75.284 million km).

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

Addendum

May Star Chart

May 2016 Star Chart

Star Chart for May 2016. Created using my LookingUp program. To enlarge in Firefox Right-click on image then click View Image.

The planets and stars are plotted for the 15th at 11 p.m. EDT.  That is chart time.  Note, Traverse City is located approximately 45 minutes behind our time meridian.  (An hour 45 minutes behind our daylight saving time meridian.) To duplicate the star positions on a planisphere you may have to set it to 1:45 earlier than the current time.

Evening nautical twilight ends at 10:00 p.m. EDT on the 1st, increasing to 10:43 p.m. EDT on the 31st.

Morning nautical twilight starts at 5:20 a.m. EDT on the 1st, and decreasing to 4:38 a.m. EDT on the 31st.

Add a half hour to the chart time every week before the 15th and subtract a half hour for every week after the 15th.  Before the 13th also subtract an hour for Standard Time.

For a list of constellation names to go with the abbreviations click here.

  • Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star
  • A leaky Big Dipper drips on Leo
  • Follow the arc of the handle of the Big Dipper to the star Arcturus
  • Extend the ac to a spike to point to Spica

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 Time.  Some additions made to aid clarity.

    Date   Time      Event
May 01 Su            Venus: 9.8° W
    02 Mo  9:27 p.m. Moon Descending Node
    04 We  2:45 p.m. Eta Aquarid Shower: ZHR = 60
    06 Fr 12:14 a.m. Moon Perigee: 357800 km
    06 Fr  3:30 p.m. New Moon
    08 Su  4:21 a.m. Moon-Aldebaran: 0.5° S
    09 Mo  7:12 a.m. Mercury transit begins
    09 Mo 10:57 a.m. Mercury mid-transit
    09 Mo  2:42 p.m. Mercury transit ends
    09 Mo  5:54 p.m. Moon North Dec.: 18.4° N
    13 Fr  1:02 p.m. First Quarter
    14 Sa  3:06 a.m. Moon-Regulus: 2.5° N
    15 Su  5:30 a.m. Moon-Jupiter: 2.2° N
    15 Su  4:39 p.m. Moon Ascending Node
    18 We  6:06 p.m. Moon Apogee: 405900 km
    21 Sa  5:15 p.m. Full Moon
    22 Su  7:15 a.m. Mars Opposition
    22 Su  5:59 a.m. Moon-Saturn: 3.5° S
    24 Tu  7:16 a.m. Moon South Dec.: 18.5° S
    29 Su  8:12 a.m. Last Quarter
    30 Mo 12:45 a.m. Moon Descending Node
    30 Mo  5:36 p.m. Mars closest to the Earth 0.50321 AU
Jun 01 We            Venus: 1.5° W

Transit of Mercury

May 9, 2016 7:12 a.m. (11:21 UT) to 2:42 p.m. (18:42 UT)

rack of the Transit of Mercury

The track of Mercury across the face of the Sun. Mercury will travel from upper left to lower right. Mercury will not be visible until it impinges upon the disk of the Sun. Credit IOTA’s program Occult4.

Transit Map

The map showing where the transit is visible in whole or in part. If using Firefox enlarge the map by right clicking on it and select View Image.

 

04/28/2016 – Ephemeris – The adventures of Corvus, Apollo’s pet crow

April 28, 2016 Comments off

Ephemeris for Thursday, April 28th.  The Sun rises at 6:36.  It’ll be up for 14 hours and 8 minutes, setting at 8:44.   The Moon, 1 day before last quarter, will rise at 2:20 tomorrow morning.

The small constellation of Corvus the crow is located low in the south at 11 this evening. It’s made of 5 dim stars, but the pattern is a distinctive distorted box with two stars at the upper left marking that corner. To the right is a fainter constellation of a thick stemmed goblet called Crater. Both appear above the long constellation of Hydra the water snake who is slithering just above the southern horizon.. In Greek mythology Corvus, then white, was the god Apollo’s pet. Apollo once bid Corvus to take a cup and fetch him some water. Corvus however dallied and waited for a green fig to ripen. Corvus grabbed a snake and returned with a story as to how the snake had delayed him.  The angry Apollo turned the crow and all crows to this day black.

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

Addendum

Corvus the crow, Crater the cup and Hydra the water snake

Corvus the crow, Crater the cup and Hydra the water snake along with Jupiter and the other spring stars at 10 p.m. April 28, 2016. Created using Stellarium.

04/27/2016 – Ephemeris – Mars is closing in on its rival, but backs off for now

April 27, 2016 Comments off

Ephemeris for Wednesday, April 27th.  The Sun rises at 6:38.  It’ll be up for 14 hours and 5 minutes, setting at 8:43.   The Moon, 2 days before last quarter, will rise at 1:36 tomorrow morning.

Let’s see what the bright naked eye planets are up to.  Mercury is in the west-northwest, very low to the horizon, setting at 10:12 p.m.  Mercury is really fading now.  Jupiter is in the southeast in the early evening, and will pass due south at 10:17 p.m., and will set at 4:51 a.m.  It’s below the stars of Leo this year.  Binoculars can make out some of Jupiter’s moons, but a telescope is required to see all four bright moons and Jupiter’s cloud features.  Mars will rise at 11:11 p.m. in the east-southeast.  It’s now almost bu not quite directly north of its look-a-like star Antares, whose name means Rival of Mars.  Saturn will rise at 11:40 p.m. in the east-southeast.  It’s just left of Mars.  Its rings are a telescopic treat.  Venus is invisibly close to the Sun now.

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

Addendum

 

Jupiter and the spring stars

Jupiter and the spring stars animation. Set for 10 p.m. April 27, 2016. Created using Stellarium.

Jupiter and its moons

Jupiter and its moons as they might be seen in a telescope at 10 p.m., April 27, 2016. Jupiter’s apparent diameter is 41.2″ According to the Project Pluto web site the Great Red spot will cross Jupiter’s central meridian at 9:16 p.m., a half hour after sunset. If so, the position of the spot in this chart is incorrect. Created with Cartes du Ciel (Sky Charts).

Mars, Saturn and the Moon

Mars, Saturn and the Moon at 5:30 a.m. April 28, 2016. Created using Stellarium.

Mars as seen in a powerful telescope

Mars as it might be seen in a large telescope with high power at 5:30 a.m., April 28 2016. Mars apparent diameter is 15.7″. The central meridian will be 169.90 degrees. Created using Cartes du Ciel (Sky Charts).

Saturn and its moons

Saturn and its moons at 5:30 a.m., April 28, 2016. The apparent diameter of the planet will be 18.1″. The rings span 42.1″, a bit larger than the apparent diameter of Jupiter. Created using Cartes du Ciel (Sky Charts).

The Moon as it might appear in binoculars

The Moon as it might appear in binoculars at 5:30 a.m. on April 28, 2016. Created using Stellarium.

 

The retrograde tracks of Mars and Saturn

The retrograde tracks of Mars and Saturn as we pass both planets this year. The tracks start on February 14, 2016 and run to September 13, 2016 plotted at 4 day intervals and labeled every 20 days. I noticed when producing the Mars, Saturn & Moon plot above that Mars was not due north of Antares on the 27th. Mars actually became stationary and started it’s retrograde loop a few days ago before it got that far. However when Mars doubles back, it will have a much closer pass of Antares on August 27th. Saturn’s plots are so close together that they appear as a fat line. Created using Cartes du Ciel (Sky Charts).

Retrograde motion of the planets are caused when the Earth is either passing a superior planet (Mars, Jupiter, Saturn, etc.), or when being passed by an inferior planet (Venus and Mercury).  It was a big problem with the old Earth center solar system, before Copernicus and Kepler.

Sunset to sunrise on a single night

Planets at sunrise and sunset of a single night starting with sunset on the right on April 27, 2016. The night ends on the left with sunrise on April 28. If you are using Firefox right-click on the image and select View Image to enlarge the image. That goes for all the large images.

04/26/2016 – Ephemeris – Arcturus, just passing through

April 26, 2016 Comments off

Ephemeris for Tuesday, April 26th.  The Sun rises at 6:39.  It’ll be up for 14 hours and 2 minutes, setting at 8:42.   The Moon, 3 days before last quarter, will rise at 12:48 tomorrow morning.

Arcturus is an orange-colored giant star, 37 light years away.  We see it high in the east and pointed to by following the arc of the handle of the Big Dipper.  Arcturus is a rapidly moving star.  It’s velocity is about 76 miles per second (122 km/s).  It’s almost at its nearest to the Sun now.  In the next 2,000 years it will move about one degree, twice the width of the Moon toward Spica.  Arcturus may be part of a dwarf galaxy being assimilated by the Milky Way which may account to its odd motion.  Arcturus is thought to be close to 8% more massive than the Sun and about 6 to 8 ½ billion years old.  It has entered its red giant stage after running out of hydrogen in its core.  It may be a glimpse of what the sun will look like in 5 billion years.

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

Addendum

Arcturus in motion.

The constellation Bootes and the 4th brightest star in the night sky. The thin line extending to the right from Arcturus is the distance it will travel in the next 2,000 years. That line is nearly one degree ling, or 2 Mon diameters. Created using Cartes du Ciel (Sky Charts)

Categories: Ephemeris Program, stars Tags:
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