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04/21/2017 – Ephemeris – Mars is passing south of the Pleiades today

April 21, 2017 Comments off

Ephemeris for Friday, April 21st.  The Sun rises at 6:47.  It’ll be up for 13 hours and 47 minutes, setting at 8:35.  The Moon, 2 days past last quarter, will rise at 4:54 tomorrow morning.

Mars in its ever eastward trek through the constellations of the Zodiac is now just south of the Pleiades or Seven Sisters star cluster in the western evening twilight.  By 10 p.m. Mars will be 10 degrees above the western horizon.  That’s the width of a fist held at arm’s length.  Because of our location on the Earth, the setting sky is tilted, so Mars being south of the Pleiades is to the lower left of it.  The bright star Aldebaran, now brighter than Mars is to the left of it with the V-shaped star cluster called the Hyades, in mythology, half sisters of the Pleiades, filling out the face of Taurus the bull.  Mars will finally be overtaken by the Sun on July 26th.  After that it will spend more than a year to come closer to us than at any time since August 2003.

First star party of the year at the Sleeping Bear Dunes National Lakeshore

Tomorrow night the Rangers of the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society will host a Star Party at the Dune Climb featuring the planet Jupiter, and the stars of spring.  It starts at 9 p.m.

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

Addendum

Mars passes the Pleiades

Mars and the Pleiades at 10 p.m. April 21, 2017. Aldebaran and the Hyades which is the face of Taurus the bull is to the left of them. Created using Stellarium.

Note that the nebulosity in the Pleiades exists, but is not visible to the naked eye.

04/20/2017 – Ephemeris – The Lyrid meteors are reaching their peak now

April 20, 2017 Comments off

Ephemeris for Thursday, April 20th.  The Sun rises at 6:49.  It’ll be up for 13 hours and 44 minutes, setting at 8:33.  The Moon, 1 day past last quarter, will rise at 4:20 tomorrow morning.

We are in a period where the Lyrid meteors appear.  This capricious shower peaks at various times and with a variety of peak numbers from 14 to 90 per hour.  The expected peak will be April 22nd at 8 a.m.   The radiant point, from where the meteors seem to come, lies between the constellation Lyra and its bright star Vega and Hercules to the west of it.  The radiant point starts the evening low in the northeast and moves nearly overhead when the Moon finally rises.  The meteors, sometimes called falling stars will appear all over the sky, but can be traced back to that radiant point.  The best time to see these or any meteor shower is when the radiant point is highest in the sky.  That will be Saturday morning.

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

Addendum

Lyrid  Radiant.

Location of the Lyrid meteor radiant at midnight. Note that the radiant point is a spot that the meteors can be back tracked to. The meteors will appear all over the sky. If they appear near the radiant they will appear to move the slowest, since their actual motion is mostly toward the observer. Created using Stellarium.

The display of meteor shower radiants is a plug-in in the latest versions of Stellarium.

04/17/2017 – Ephemeris – How to find the stars Arcturus and Spica from the Big Dipper

April 17, 2017 Comments off

Ephemeris for Monday, April 17th.  The Sun rises at 6:54.  It’ll be up for 13 hours and 35 minutes, setting at 8:30.  The Moon, 2 days before last quarter, will rise at 2:21 tomorrow morning.

The Big Dipper, now nearing the zenith at 10 p.m. points to several stars and constellations.  It’s handle points to two bright stars.  First we follow the arc of the handle to the bright orange star Arcturus, the 4th brightest night-time star.  The reason I say night-time is that the sun is a star also but by definition is not out at night.  The arc to Arcturus is a how to find Arcturus and a clue to its name.  Arcturus, midway up the sky in the east, lies at the base point of the kite shaped constellation of Boötes the herdsman.  From Arcturus, straighten out the arc to a spike and one soon arrives at Spica a blue-white star in Virgo the virgin, now low in the southeast.  It is below Jupiter this year.  Spica is also sometimes pronounced ‘Speeka’.

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

Addendum

Finding Arcturus and Spica

How to find the stars Arcturus and Spica from the Big Dipper in April 2017. Created using my LookingUp program.

04/10/2017 – Ephemeris – Jupiter takes over as king of the evening sky

April 10, 2017 Comments off

Ephemeris for Monday, April 10th.  The Sun will rise at 7:06.  It’ll be up for 13 hours and 14 minutes, setting at 8:21.  The Moon, 1 day before full, will set at 7:36 tomorrow morning.

By the time we see the Moon tonight it will be about 5 hours from officially being full.  However bright planet Jupiter should be easily visible about 5 moon diameters to the right and a bit above the Moon.  In a small telescope it is easy to see the disk of Jupiter, and possible see the cloud bands in the atmosphere,  due to the planet’s rapid rotation, of less than 10 hours.  Jupiter’s mass is over 300 times the Earth’s, while one could squeeze over a thousand Earth’s into its volume.  Jupiter has something like 67 satellites,  but only for are visible in small to medium telescopes.  Tonight they will be strung out all on one side of Jupiter, tomorrow night two will be on the other side of the planet, and another will be playing peek-a-boo in front of Jupiter.

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

Addendum

 

Jupiter on two nights

Jupiter and its moons in a telescope at 10 p.m. both April 10th & 11th, 2017. Created using Cartes du Ciel (Sky Charts).

Event Date & Time EDT Date & Time UT
Io Occultation Start 10 April 2017 10:31 p.m. 11 April 2017 2:31
Io Eclipse ends 11 April 2017 12:28 a.m. 11 April 2017 4:46
Ganymede Occultation start 11 April 2017 4:28 a.m. 11 April 2017 8:28
Ganymede Eclipse end Not visible 11 April 2017 11:02
Europa Occultation start Not visible 11 April 2017 18:44
Europa Eclipse ends Not visible 11 April 2017 21:19
Io Transit starts Not visible 11 April 2017 23:48
Io Shadow ingress Not visible 11 April 2017 23:54
Io Transit ends 11 April 2017 8:58 p.m. 12 April 2017 1:58
Io Shadow egress 11 April 2017 10:05 p.m. 12 April 2017 2:05

Where times EDT show as not visible, Jupiter is below the horizon.  Date and time UT are for observers in other locations.  UT is Universal Time, or Greenwich Mean Time.

Occultation = moon passes behind Jupiter
Eclipse = moon in Jupiter’s shadow
Transit = moon passes in front of Jupiter
Shadow = moon’s shadow is cast on the face of Jupiter

 

03/30/2017 – Ephemeris – Have you ever seen zodiacal light?

March 30, 2017 Comments off

Ephemeris for Thursday, March 30th.  The Sun will rise at 7:26.  It’ll be up for 12 hours and 41 minutes, setting at 8:07.  The Moon, 3 days past new, will set at 11:23 this evening.

After you spot the moon tonight, hang around outside at the end of astronomical twilight, about 9:50 p.m. look to the west at Taurus the bull and Gemini, trying to block out the Moon.  Then broaden your gaze.  There will be a very faint triangular glow with broad base at the horizon leaning a bit to the left, with its apex near the V of the face of Taurus the bull and the bright star Aldebaran to the right of Orion.  This glow is called Zodiacal Light, caused by the reflected sunlight off a cloud of dust located in the plane of the solar system.  Most of the large bodies of the solar system orbit the sun close to a single plane.  Zodiacal Light is best seen on spring evenings and autumn mornings where it tilts to the right.

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

Addendum

Zodiacal Light and Comet Hale-Bopp April 1997

Zodiacal Light and Comet Hale-Bopp April 1997. My image.

03/19/2017 – Ephemeris Extra – Comet 41P/Tuttle-Giacobini-Kresak is within reach of binoculars and small telescopes

March 19, 2017 Comments off

UT

Comet 41P finder chart

Comet 41P finder chart for the next month, March 20 to April 19. It is expected to be brightest at magnitude 6.6 in early April. Comet positions and orientation in the northeast are for 11:30 p.m. on the date specified or 3:30 UT on the next date. Created using Cartes du Ciel (Sky Charts).  Click on the chart to enlarge.

Note above:  The tail symbol points to the direction of a tail.  However none of the photographs I’ve seen show a tail, so none will be visible visually.

This comet is known to have frequent outbursts where its brightness increases by many times.  If an outburst occurs in early April, the comet could become visible to the naked eye.   Original source material for this post comes from Seiichi Yoshida’s Weekly Information about Bright Comets web page.  The comet will pass less than 14 million miles (22 million km) from Earth on April 5th, only 8 days before it’s closest approach to the Sun, called perihelion.  From the finder chart one can see the comet will pass to the north of the Earth.

According to Gary Kronk’s Cometography.com web site the comet was discovered and lost three times.  It was first discovered in 1858 by Horace Tuttle, whose name was attached to at two well known comets that produce meteor showers.  It was unobserved for the next eight returns, which were expected every 5.42 years.  Michel Giacobini rediscovered it again in 1907.  Giacobini was the discoverer of Comet Giacobini-Zinner, another famous meteor shower producing comet.  It was lost again until Lubos Kresák rediscovered it in 1951 after seven more missed returns.

11/28/2016 – Ephemeris – The Hyades the star cluster in the face of Taurus the bull

November 28, 2016 Comments off

Ephemeris for Monday, November 28th.  The Sun will rise at 7:57.  It’ll be up for 9 hours and 7 minutes, setting at 5:04.  The Moon, 1 day before new, will rise at 7:45 tomorrow morning.

Rising in the east now is the bright star Aldebaran an orange star that’s at one end of the sideways letter V of stars that is the head of Taurus the bull.  Above it is the jewel-like Pleiades or Seven Sisters star cluster.  There’s more to Taurus, like it’s freakishly long horns and front part of its body.  But you can say you’ve seem Taurus, if you can spot his face.  That V of stars is actually a star cluster called the Hyades, and in Greek Myth were the half-sisters of the Pleiades, also fathered by the god Atlas.  Both the Hyades and Pleiades are being pursued by Orion, which as Robert Frost put it is throwing a leg over the eastern horizon at 8 to 9 pm.  He isn’t the only one following the Pleiades, the name Aldebaran means “The Follower”.

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

Addendum

the Hyades, Taurus, Orion and the Pleiades

An animation showing the Hyades, Taurus, Orion and the Pleiades. Created using Stellarium and GIMP.  Click on image to enlarge.

Closeup of the Hyades and the Pleiades

Closeup of the Hyades and the Pleiades. Created using Stellarium.