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10/19/2020 – Ephemeris – This zodiacal constellation seems fishy

October 19, 2020 Leave a comment

This is Bob Moler with Ephemeris for Monday, October 19th. Today the Sun will be up for 10 hours and 46 minutes, setting at 6:50, and it will rise tomorrow at 8:05. The Moon, 3 days past new, will set at 8:58 this evening.

High in the southeast at 9 p.m. are the four bright stars of the Great Square of Pegasus, the upside down flying horse. Lying along the left and bottom sides of the great square is the constellation of Pisces the fish, one of the 12 constellations of the Zodiac. Even though the constellation is called the fish, the fish themselves are not well represented in the stars. What can be traced in the stars is the rope, that’s tied to their tails, anchored at the extreme southeastern part of the constellation that is seen in the stars. It is near where the bright red planet Mars currently is. The right or western end of Pisces is the asterism, or informal constellation, of the Circlet. It’s the loop of 5 stars, the rope around the tail of one of the two fish.

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

Addendum

Pisces finder animation

Pisces finder animation showing the Great Square of Pegasus as a way to find it, though this year bright Mars will show where it is. Created using Stellarium and GIMP.

Mars' apparent path for the rest of 2020

Mars’ apparent path for the rest of 2020 stays within Pisces. Mars doesn’t do a loop de loop as the ancients thought when they thought the Earth was motionless. It’s the effect of the Earth passing Mars in their orbits. Mars will stop its westward or retrograde motion around November 13th and resume its normal eastward motion. This view created using Cartes du Ciel (Sky Charts).

10/15/2020 – Ephemeris – The Great Andromeda Galaxy

October 15, 2020 Leave a comment

This is Ephemeris for Thursday, October 15th. Today the Sun will be up for 10 hours and 58 minutes, setting at 6:57, and it will rise tomorrow at 8:00. The Moon, 1 day before new, will rise at 7:30 tomorrow morning.

The closest large galaxy to our Milky Way galaxy is the Great Andromeda Galaxy seen in the eastern sky when it gets dark. It is barely visible to the naked eye. To locate it first find the Great Square of Pegasus high in the east, standing on one corner. The left star of the square is the head of the constellation Andromeda. Follow two stars to the left and a bit downward, then two stars straight up. The galaxy is near that last star as a small smudge of light. Binoculars are the best way to see it as a thin spindle of light. Visually through a telescope one can see only the bright nucleus of the galaxy, that spans six Moon diameters in photographs. M31 is its most famous catalog designation and it is two and a half million light years away.

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

Addendum

Andromeda and M31 animated finder

Andromeda animated finder, including the Great Andromeda Galaxy. I’ve added Cassiopeia that some folks use to find the galaxy. I start with the leftmost star of the Great Square of Pegasus that connects to Andromeda. I count off two star on the lower curve because they are brighter than the upper curve. Then count two stars up. Next to that top star is a little smudge. That is the core of the Great Andromeda Galaxy. Created using Stellarium and GIMP.

The moon superimposed on M31 for apparent size comparison

The moon superimposed on the Great Andromeda Galaxy, M31, for apparent size comparison. Created using Stellarium and the embedded image of the galaxy with that of the full Moon of October 31, 2020. M31 Image credit: Herm Perez License: “Feel free to use these images, if you use them in a commercial setting please attribute the source.”

 

08/27/2020 – Ephemeris – Unsolved mysteries: Dark Matter

August 27, 2020 Comments off

This is Ephemeris for Thursday, August 27th. Today the Sun will be up for 13 hours and 27 minutes, setting at 8:27, and it will rise tomorrow at 7:01. The Moon, 2 days past first quarter, will set at 1:58 tomorrow morning.

It was in the 1930s that some astronomer concluded by measuring the velocities of individual galaxies that galaxy clusters contain more mass that can be explained by the size and brightness of the galaxies within. Fritz Zwicky coined the term dark matter for it after his study in 1933. Vera Rubin and others discovered the effect of dark matter on the rotation rates of galaxies in the 1960s and 70s. Nobody knows what dark matter is. There are two leading theories that they are made of particles coined WIMPs and objects called MACHOs that don’t interact with normal matter except gravitationally. Astronomers do have fun with their acronyms. Dark matter is detected by their gravity and how it distorts the light from the galaxies behind it.

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

Addendum

Bullet Cluster showing what happened to the dark matter

This is called the Bullet Cluster. It’s two galaxy clusters that collided. The pink is hot gas visible in x-rays. The blue is added to show where dark matter resides. It is detected by studying the far distant galaxies beyond for distortion caused by the gravitational lensing of the dark matter. Most of the mass of the galaxy clusters is dark matter, which also contain hot gas and, of course the galaxies. When galaxy clusters collide the gas of the two clusters interact and are stripped out and the dark matter and galaxies go merrily on. Image Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University)

FYI: WIMPs = Weakly Interacting Massive Particles, MACHOs = MAssive Compact Halo Objects.

08/25/2020 – Ephemeris – The Great Andromeda Galaxy will collide with the Milky Way someday

August 25, 2020 Comments off

This is Ephemeris for Tuesday, August 25th. Today the Sun will be up for 13 hours and 33 minutes, setting at 8:30, and it will rise tomorrow at 6:58. The Moon, at first quarter today, will set at 12:26 tomorrow morning.

Stars are at extreme distances compared to their sizes, even if one includes their planetary systems. Galaxies in a galaxy cluster are much closer with respect to their size. Astronomers have determined that our Milky Way galaxy will collide with the Great Andromeda galaxy, some two and a half million light years away, in about four and a half billion years. Don’t worry, it is very unlikely that any stars will collide during the event, though the solar system may be in for a wild ride. As the galaxies approach each other their beautiful spiral structures will begin to distort into tidal tails. Multiple passes of the two will occur before they will coalesce into one large elliptical galaxy. Other galaxies of the Local Group will join in over time.

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

Addendum

Colliding galaxies. Note the tidal tails. Credit: Hubble Legacy Archive, ESA, NASA.

View from Earth-Andromeda collision

Original caption: This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger)

08/24/2020 – Ephemeris – The Milky Way’s companion galaxies

August 24, 2020 Comments off

This is Bob Moler with Ephemeris for Monday, August 24th. Today the Sun will be up for 13 hours and 36 minutes, setting at 8:32, and it will rise tomorrow at 6:57. The Moon, 1 day before first quarter, will set at 11:51 this evening.

Not long after spiral nebulae were confirmed to be milky ways like ours or galaxies it was noticed that they were often found in bunches or clusters. One of the closest is the Virgo cluster seen in spring covering the constellation of Virgo and adjacent constellations. Our Milky Way Galaxy has two small satellite galaxies, the Clouds of Magellan first spotted by European eyes on his epic voyage, and belongs to a small cluster of galaxies along with the Great Andromeda galaxy. Perhaps 80 galaxies belong in all, most are small irregular dwarf galaxies, difficult to find and see. Our galaxy cluster is known simply as the Local Group. The galaxies of the Local Group interact gravitationally with each other.

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

Addendum

The Magellanic Clouds

The Small and Large Magellanic Clouds, these dwarf galaxies are seen best from the southern hemisphere. Credit: ESO S. Brunier.

The Great Andromeda Galaxy (M31). Image taken by Scott Anttila.

The Great Andromeda Galaxy (M31) is the largest member of the Local group with two of its satellite galaxies M32 to the left and M110 below-right. M31 can be spotted with the naked eye on fall and winter nights with the naked eye. Image taken by Scott Anttila.

M33, the Triangulum Galaxy

M33, the Triangulum Galaxy is the third largest galaxy in the Local Group after Andromeda and the Milky Way. It appears in the sky just east of the constellation of Andromeda in Triangulum the triangle. Though large it has a very low surface brightness making it hard to spot with binoculars or a telescope. Credit: Scott Anttila.

Virgo cluster

Some of the brighter members of the Virgo Cluster (of galaxies) as red ovals. The galaxies marked with an ‘M’ number are part of Charles Messier’s catalog. It took a telescope of 8 inch diameter for me to spot them. Someone with better vision, like Messier himself can spot them with a smaller telescope. Created using Cartes du Ciel (Sky Charts).

08/21/2020 – Ephemeris – Great moments in astronomy: The Great Debate in 1920

August 21, 2020 Comments off

This is Bob Moler with Ephemeris for Friday, August 21st. Today the Sun will be up for 13 hours and 44 minutes, setting at 8:37, and it will rise tomorrow at 6:54. The Moon, 3 days past new, will set at 10:26 this evening.

One hundred years ago there were two lectures given to the National Academy of Science by Drs. Harlow Shapley and Heber Curtis. This became know as the Great Debate. Shapley believed that the Milky Way was the entire universe, and evidenced by the distribution of globular star clusters in the sky that the Sun was near the periphery of it, and that spiral nebulae were part of the Milky Way. Curtis on the other hand thought that the Sun was near the center of the Milky Way, however that the spiral nebulae were other island universes, or milky ways of their own. Over the next decade each was proved right in part and wrong in part. We are not near the center of the Milky Way, but those spiral nebulae were indeed other milky ways or galaxies.

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

Addendum

M51 drawing

A drawing of the Whirlpool Galaxy, M51 (NGC 5194 & 5195) by Lord Rosse with his 72 inch telescope in the mid 19th century. This is the only “spiral nebula” I have actually seen as a spiral visually in a telescope, though not as well as he saw it. Public Domain.

M51 photo

With the advent of photography many spiral nebulae were discovered. The Whirlpool Galaxy, M51. Credit Scott Anttila.

Press Release for the Great Debate

This is a copy of the Press release issued for the two presentations of Harlow Shapley and Heber Curtis at the annual meeting of the National Academy of Sciences April 26, 1920 that have come to be known as the “Great Debate”. Credit NAS.

For more on the Great Debate follow this link.

Astronomy has advanced a long way in the last 100 years.  And what’s crazy is that I actually met Dr. Harlow Shapley at the opening of the Planetarium of the Grand Rapids Public Museum around 1960. I was in my first year at Grand Rapids Junior College at the time. I had been a member of the of the local astronomy club for several years by then. Two friends and I became planetarium rats and have wormed our way into volunteering to working with it before a formal structure was set up to operate it.

 

05/15/2020 – Ephemeris – Virgo and its cluster of galaxies

May 15, 2020 Comments off

This is Ephemeris for Friday, May 15th. Today the Sun will be up for 14 hours and 50 minutes, setting at 9:04, and it will rise tomorrow at 6:12. The Moon, 1 day past last quarter, will rise at 4:01 tomorrow morning.

One of the large constellations we see in the south at 11 p.m. can be found using the Big Dipper overhead, follow the arc of the handle to the bright star Arcturus, the straighten the arc to a spike to reach Spica, a bright blue-white star in the south. Spica is the brightest star in the constellation Virgo the virgin. She represents the goddess of the harvest, Virgo is holding a sheaf of wheat in depictions of her, and Spica is placed at the head of the sheaf. In the space between Spica and Leo the lion to her upper right is, a great cluster of thousands of galaxies just below naked eye visibility. The Virgo Cluster. Inside that cluster is galaxy M87 in whose center lies a black hole with the mass of 6.5 billion suns that was imaged last year. The center of the cluster is at about 54 million light years away.

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

Addendum

Finding Spica

Spica finder animation . Click on the image to enlarge. Created using Stellarium and GIMP.

Virgo Cluster

Some of the brighter members of the Virgo Cluster (of galaxies) as red ovals. The galaxies marked with an ‘M’ number are part of Charles Messier’s catalog. It took a telescope of 8 inch diameter for me to spot them. Someone with better vision, like Messier himself can spot them with a smaller telescope. M53 and the object next to it are globular star clusters in the outer reaches of our galaxy. Created using Cartes du Ciel (Sky Charts).

Markarian Chain of galaxies

Markarian Chain of galaxies within the Virgo Cluster by Scott Anttila.

Black hole in M87

The first image of the black hole in M87. Credit Event Horizon Telescope.

 

 

05/20/2019 – Ephemeris – Dark evening skies again and a look at Virgo

May 20, 2019 Comments off

Ephemeris for Monday, May 20th. Today the Sun will be up for 15 hours even, setting at 9:09, and it will rise tomorrow at 6:08. The Moon, 2 days past full, will rise at 11:10 this evening.

One of the large constellations we see in the south at 11 p.m. can be found using the Big Dipper overhead, follow the arc of the handle to the bright star Arcturus, the straighten the arc to a spike to reach Spica, a bright blue-white star in the south. Spica is the brightest star in the constellation Virgo the virgin. She represents the goddess of the harvest, Virgo is holding a sheaf of wheat in depictions of her, and Spica is placed at the head of the sheaf. In the space between Spica and Leo the lion to her upper right is, a great cluster just below naked eye visibility. The Virgo cluster of galaxies. Inside that cluster is galaxy M87 in whose center lies a black hole with the mass of 6.5 billion suns that was imaged last month.

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

Addendum

Virgo finder

Virgo finder animation for 11 p.m. May 20, 2019. Click on the image to enlarge. Created using Stellarium.

Brighter members of the Virgo Cluster. Created using Stellarium.

Brighter members of the Virgo Cluster. Created using Stellarium. Open circles are galaxies, circles with crosses are globular star clusters, outlying members of our Milky Way galaxy.  M87 is just above center in that knot of galaxies.  Created using Stellarium.

Virgo Cluster

A closer look at some of the galaxies in the heart of the Virgo Cluster. M87 is near the center. Created with Cartes du Ciel (Sky Charts).

 

11/09/2018 – Ephemeris – The Great Andromeda Galaxy

November 9, 2018 Comments off

Ephemeris for Friday, November 9th. The Sun will rise at 7:31. It’ll be up for 9 hours and 49 minutes, setting at 5:21. The Moon, 2 days past new, will set at 7:03 this evening.

In the south at 9, this evening can be found a large square of stars, the Great Square of Pegasus the flying horse, flying upside down to the right. What looks like its hind legs stretching to the left from the upper left corner star is another constellation, Andromeda the chained princess. She is seen in the sky as two diverging curved strings of stars that curve upward. She was rescued by the hero Perseus, a nearby constellation, riding Pegasus. Andromeda’s claim to astronomical fame is the large galaxy seen with the unaided eye just above the upper line of stars. The Great Andromeda Galaxy is 2.5 million light years away. To the naked eye the galaxy appears as a small smudge of light. In binoculars the galaxy is a delicate spindle of light.

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

Addendum

Great Andromeda Galaxy finder chart
Great Andromeda Galaxy finder chart. Created using Stellarium and GIMP.
The Great Andromeda Galaxy (M31). Image taken by Scott Anttila.
The Great Andromeda Galaxy (M31) with two of its satellite galaxies M32 and M110. Image taken by Scott Anttila.

06/25/2018 – Ephemeris – Andromeda’s Parachute

June 25, 2018 Comments off

Ephemeris for Monday, June 25th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 3 days before full, will set at 5:02 tomorrow morning.

A recent post of Dr. Phil Plait’s Bad Astronomy Blog caught my eye. The object discovered is being called Andromeda’s Parachute. It has three relatively bright star-like points arranged in an arc like a parachute canopy, with another star-like point beneath it as the parachutist. It is the light from a single quasar, an active galaxy nucleus being split up by the gravitational lens of a closer, but dimmer galaxy in between us and the quasar. It’s very beautiful, and within reach of only the biggest telescopes. It was discovered using the Pan-STARRS telescope on Haleakala in Maui by George Nelson.

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

Addendum

Panstarrs_quadruple_quasar

Quadruple quasar dubbed Andromeda’s parachute. The four images (A-D) of the quadruply lensed quasar J014709+463037 can be seen in this deep image taken by the Pan-STARRS telescope. The lensing galaxy (G) is marked by an X. Credit: Berghea et al.

The Bad Astronomer’s original post