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01/24/2022 – Ephemeris – The Great Orion Nebula

January 24, 2022 Comments off

This is Ephemeris for Monday, January 24th. Today the Sun will be up for 9 hours and 30 minutes, setting at 5:40, and it will rise tomorrow at 8:09. The Moon, 1 day before last quarter, will rise at 1:03 tomorrow morning.

The closest star nursery to us, places where stars are being born, is the Great Orion Nebula, 1,300 light years away. A light year is about 6 trillion miles, if you want to pace it out. It’s located in the constellation Orion’s sword that hangs below his belt. In as little as a pair of binoculars, it shines by emission and reflection of the light of a tiny clutch of four stars at its heart, which astronomers have called the Trapezium. These extremely hot young massive stars are not destined to live long. Unlike the Sun’s 10 billion year lifetime, these stars lifespans will be measured in millions of years. Yet do not mourn for them, even now stars are forming within their dusty cocoons in the nebula. The Trapezium stars’ deaths will provide heavy elements for new stars and planets.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

The lower part of Orion with the Great Orion Nebula. Created using Stellarium.

The lower part of Orion, with the Great Orion Nebula. Created using Stellarium.

The Great Orion Nebula (M42) long exposure photograph

The Great Orion Nebula (M42) long exposure photograph by Scott Anttila. Includes all the sword stars.

Inner part of the Great Orion Nebula. Image by Scott Anttila

The inner and brightest part of the Great Orion Nebula. Also, visible are the four stars of the Trapezium, whose ultraviolet emissions light up the nebula. This is pretty much one’s perception of the nebula as seen in a small telescope, except it would appear colorless. In larger telescopes, one would perceive a greenish color. The red color of hydrogen is outside our night adapted visual range. The green emission is due to mainly doubly ionized oxygen and the green emission of hydrogen. Image by Scott Anttila.

12/10/2021 – Ephemeris – Our last look at Comet Leonard before it leaves forever*

December 10, 2021 Comments off

This is Ephemeris for Friday, December 10th. Today the Sun will be up for 8 hours and 52 minutes, setting at 5:02, and it will rise tomorrow at 8:10. The Moon, at first quarter today, will set at 12:25 tomorrow morning.

This is the day of the earliest sunset of the year. It doesn’t coincide with the shortest day because the Earth is moving faster in its orbit than average and getting ahead of its rotation a bit. Comet Leonard’s last appearance in the morning sky is tomorrow or Sunday before twilight overwhelms it. At 6:30 am it will be just a bit south of due east at azimuth 93 degrees and an altitude of 9 degrees, a bit less than the width of a fist held at arm’s length. When it gets into the evening sky, its track will take will be along the horizon from the southwest to the south. It will come very close to Venus, and I suspect that is what will alter its orbit slightly, so it will never return and end up becoming an interstellar comet.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

* After this weekend, the comet will enter the evening sky, but will hang quite low to the horizon in evening twilight as it passes Venus, heads southward and fades. It would best be viewed by observers in the Southern Hemisphere. It’s headed out of the solar system in a hyperbolic orbit.

Addendum

Comet Leonard 7 am, 12/11/21

Comet Leonard (C/2021 A1) finder chart for 7:00 am, December 11, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 22.1 million miles away, and will come within 21.7 million miles at its closest to us on the 12th. Created using Stellarium.

Comet Leonard (C/2021 A1) in the morning

Comet Leonard’s positions at 7:15 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for December 10th. The star field will be shifting to the upper right each morning at 7:15 from the December 10th date at 7:15. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. Created using Cartes du Ciel (Sky Charts).

09/03/2015 – Ephemeris – Jewels in the shield

September 3, 2015 Comments off

Ephemeris for Thursday, September 3rd.  The Sun will rise at 7:07.  It’ll be up for 13 hours and 9 minutes, setting at 8:16.   The Moon, 2 days before last quarter, will rise at 11:26 this evening.

The teapot pattern of stars that is the constellation of Sagittarius lies at the southern end of the Milky Way this evening. It appears that the Milky Way is steam rising from the spout.  The area above Sagittarius in the brightest part of the Milky Way is the dim constellation of Scutum the shield.  Don’t bother looking for the stars that make up the constellation; what’s important is the star clouds of the Milky Way.  Scan this area with binoculars or small telescope for star clusters and nebulae or clouds of gas.  In binoculars both clusters and nebulae will appear fuzzy, but a small telescope will tell most of them apart.  Even if you’ve never been able to find anything in your telescope, you’ll find something here.

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

Addendum

Scutum

Scutum between Sagittarius below and Aquila above at 10 p.m. September 3, 2015. Created using Stellarium.

Star hopping in Scutum

How to find the three brightest deep sky wonders around Scutum by star hopping. Created using Stellarium, annotated by myself.

Star hopping is a method to find objects from familiar star patterns.  At the top my method to find M11, the wild duck cluster is to locate the three stars at the tail of Aquila the Eagle and follow them to M11.  M11 takes a little bigger telescope to resolve.  I remember having trouble resolving it is a 5″ telescope.  It looks like a triangular cluster with all the stars of the same dimness except one brighter one.

At the bottom of Scutum, I locate that distinctive 5 star group circled.  Directly west is M16, the Eagle Nebula and star cluster.  The star cluster is easy to spot, the nebula is hard.  The Hubble space telescope made the nebula famous in the 1990’s as the Pillars of Creation.

Below and west is M17, the Omega Nebula, or the Swan Nebula.  To me it looks like a swan swimming or a check mark of nebulosity.  The associated star cluster is much less noticeable.

Happy star hopping.