Archive for the ‘Ephemeris Extra’ Category

Announcement: I’m offering to present Apollo and the Race to the Moon to schools, libraries and non-profits

July 2, 2019 Comments off

Apollo and the Race to the Moon is the story of the space race from Sputnik to Apollo 17 between the United States and the Soviet Union that traces the United States’ incremental steps and the Soviets’ rather disorganized approach that allowed the US to be the first on the Moon.  The presentation by yours truly will be illustrated by images and a short video.

I will be giving this presentation as a NASA/JPL Solar System Ambassador.  The presentation will be given free of charge for non-profit groups, libraries and schools.  I can be reimbursed for expenses if traveling over 50 miles from Traverse City, MI.  The presentation lasts a bit over an hour depending on the number of questions, which I welcome.

Apollo and the Race to the Moon Title

Apollo and the Race to the Moon Title slide

I’ve been an avid amateur astronomer and space enthusiast since before the launch of Sputnik, so I have lived through all these events.  For more information on me click on the About link above.  There’s even a timeline of my astronomy activities here.  The About link above contains a contact form where you can reach me.


Categories: Ephemeris Extra

05/06/2019 – Ephemeris Extra – The Eta Aquariids – Halley’s Comet never really left

May 5, 2019 Comments off

In 1986 Halley’s Comet swam through our skies for the 28th time since the Chinese first recorded it in 240 BCE. It was not especially impressive, considering the week when my family met a group of Leelanau School students in the Florida Keys the week in April 1986 to view and photograph the comet at it’s closest to the Earth of 44 million miles. It turned out that that week the comet lost its tail, probably due to a coronal mass ejection from the Sun. Halley’s Comet was much more impressive a month later. I’ve seen more impressive comets before and since.

Comet Halley's path thru the inner solar sstem

Comet Halley’s path through the inner solar system in 1985-86. Created using my LookingUp program.

Halley’s Comet has been swinging around the Sun countless times before the Chinese first recorded it. The illustration above shows the last time the comet entered the inner solar system in 1986. The comet’s path is from upper right to lower left. When the comet passes within about 3 astronomical units of the Sun, that is 3 times the Earth’s distance from the Sun, the ices in the comet begin to sublimate, escaping from the comet’s nucleus which liberates dust and larger solid material. The gasses and dust form the comet’s ion and dust tails. The larger material, gravel sized bits, end up in and around the comet’s orbit, and over time are spread out around and near the comet’s orbit. Halley’s orbit crosses the Earth’s orbit twice, inbound and outbound. In both cases these crossings are close enough to the plane of the Earth’s orbit to produce meteor showers.

On the inboard leg of the orbit it produces the Orionid meteor shower that peaks on October 22nd. A meteor shower is generally named for the point in the sky they seem to come from, be it a constellation or star. The point, called the radiant, moves during the days or weeks the shower is visible. The Orionids are named for the constellation Orion. The radiant is near his upraised arm.

The center of the outbound meteoroid stream crosses the Earth’s orbit where the Earth is on May 6th. Though they have a broad peak of about 5 days. This meteor shower is visible from April 19th to May28th. During that period the radiant points drifts quite a bit to the east. There are several meteor shower radiants in Aquarius, so they are named for the nearest star at peak.

Motion of Eta Aquariid Radiant

Motion of the Eta Aquariid radiant from April 20 to May 25. The triangle with the star near the center near May 05 is the asterism the Water Jar, a part of Aquarius. Eta Aquarii is the triangle star to the left. Source: PDF version of the International Meteor Organization 2019 Meteor Shower Calendar:

Though the Moon is new for this shower, the meteoroids are coming from near the direction of the Sun, so there is only an hour where the Eta Aquariids are best seen. For Northern Michigan the radiant rises at 3:30 a.m. on May 6th. Astronomical twilight begins at 4:30 a.m. when the sky begins to brighten. This meteor shower is best seen from the southern hemisphere.

02/02/2019 – Ephemeris Extra – Groundhog Day and other seasonal days

February 2, 2019 Comments off

Note:  I wrote this article as part of the Grand Traverse Astronomical Society’s Stellar Sentinel for February 2019.

Groundhog day coming this month got me to thinking about the seasons and those special seasonal days, like solstices, equinoxes and cross-quarter days. February 2nd is a cross-quarter day, supposedly when winter is half over. Below is a table I created of the seasons for one year starting with last December’s winter solstice.

I took the date and times from Astronomical Tables of the Sun, Moon and Planets, Third edition by Jean Meeus. TD is Dynamical Time, used to calculate the positions of bodies in the solar system, is about 68 seconds fast compared to Universal Time (UT), which is tied to the Earth’s rotation. The difference is slowly changing at less than a second a year and doesn’t enter into the calculations. The Julian Date is a consecutive date starting on January 1, 4713 BC at noon UT. It’s used by astronomers to calculate date differences. like the length column in the table above without worrying how many days months have or how many leap years are in the interval. If you want to convert a calendar date to a Julian date or a Julian date to calendar date go to the Naval Observatory web page here:

Note that the seasons are of different lengths. This is because the Earth’s orbit is slightly elliptical. It reached perihelion, its closest to the Sun, this year on January 3rd, and it will reach aphelion, its farthest, on July 4th. The Earth or any planet moves fastest when near perihelion. And with perihelion 14 days into winter, makes winter the shortest season. Autumn is the second shortest season 90 days compared to winter’s 89 days. Summer at nearly 94 day’s length is 4.7 days longer than winter. However we’re too far north to really notice it. Spring is second with nearly a 93 day length.

The rest of this article is based quite a bit on the web page: Common Holidays in Relation to Equinoxes, Solstices & Cross-Quarter Days – It’s a cool list. is the website of the Arecibo Observatory in Puerto Rico. Apparently it was someone’s (Gibson’s) personal post.

The equinoxes and solstices are quarter days, for the four seasonal quarters of the year. The table above has Mid-Season and Date for the half way point in the season. The Cross-Quarter Days column are the dates which are more or less celebrated down throughout history.

The first celebrated cross-quarter day is February 2nd, Groundhog Day Which the famous weather prognosticating rodent in Punxsutawney, PA forecasts the length of winter based on if he sees his shadow. Supposedly, if he sees his shadow winter will last for six more weeks, if he doesn’t then spring is just around the corner. Actually from February second to the vernal equinox is six and a half weeks. If we had a winter like last year with a snowy April, winter lasted until the second cross-quarter day. The actual first cross-quarter day this year is February 4th. February 2nd, 40 days after Christmas, is also celebrated as Candlemas Day, when candles are blessed for the year, and the Feasts of the Purification of the Virgin Mary and The Presentation of the Child Jesus by the Catholic and some other Christian Churches.

The first quarter day is the vernal equinox, which occurs in our time zone on March 20th. The Ides of March, the 15th is pretty close to the vernal equinox and was the start of the year for a time with the Romans. It was the date in 44 BC that Julius Caesar was assassinated. March, named after the god Mars was also for a long time the first month of the year. They, for a time had 10 months, and consigned the winter months to ?. Later they added two months in front of March, which is why our 9th through 12th months are named September (7), October (8), November (9) and December (10).

The second cross-quarter day to be celebrated is May 1st, May Day. The actual 2nd cross-quarter day this year is May 6th.

The second quarter day, the summer solstice is on June 21st. It’s near midsummer day, the 24th, the feast of St. John the Baptist. It’s a big deal in Europe. If you had a midsummer’s night dream it would be on the night of June 23-24. Of course if that date was really midsummer, summer would have to start in early May.

The third cross-quarter day is August 1st, Lughnasadh. This is Celtic. It was the wedding day of Lugh, their sun god with the goddess of the Earth. This causes the crops to ripen in time to harvest in the fall. The actual date this year is August 7th.

The third quarter day is the autumnal equinox. This year it’s on September 23rd.

The fourth cross-quarter day is celebrated on October 31st, Halloween. It is the day before All Saints Day, and Day of the Dead in Mexico. The actual cross-quarter day this year is November 7th.

The fourth quarter day is the winter solstice, December 21st. This is in the midst of festivals ancient and modern around the time the Sun starts heading north again. Festivals of light, like Saturnalia, Yule, Christmas, and Hanukkah

There you have the days of our seasons.

Categories: Ephemeris Extra, Seasons

01/20/2019 – Ephemeris lunar Eclipse extra

January 20, 2019 Comments off

For those of us who may be socked in tonight we have a link to the livestream of the eclipse.

This is the link:

I subscribe to their email notices, which explains the end of the URL.

You can go to their main site: and scroll down to Upcoming Activities and Total Lunar Eclipse then Watch live online.  That connection is real slow now.

Update 9:p.m. EST:

Looks like they are having clouds over LA.  However we (Interlochen/Traverse City, MI) are partly cloudy with more clear spots than clouds, and the clouds seem to be thin.  The GOES satellite is showing a thin lake effect flow from the north.  So maybe we might pull this one off.

GOES Great Lakes cloud animation

GOES Great Lakes cloud animation for 9 p.m. Credit NOAA.

12/15/2018 – Ephemeris Extra – Finally the skies cleared and I got a photograph of Comet Wirtanen

December 15, 2018 Comments off
Comet Wirtanen and the Pleiades

Comet 46P/Wirtanen and the Pleiades. 9:24 p.m. EST, December 14, 2018. Canon EOS Rebel T5, f/5.5, 30 sec., ISO-3200, fl 55mm, tracking.  Click on the image to enlarge.  Credit Bob Moler.

Finally, the skies cleared.  The last time we had clear skies was early in the evening on the 8th. Our family went to the Ballet that evening at Interlochen Center for the Arts, and by the time I got back and dressed to go outside and observe the comet, it had clouded up.  The Ballet was wonderful, by the way.

Anyway, Comet 46P/Wirtanen as a few hours ago was greatly hampered by the nearly first quarter Moon.  And it’s going to get worse as the moon’s phase gets fuller.  I thought I could see it in with the naked eye.  It was visible in binoculars.  As you can see it did photograph well.  I processed the image with GIMP to increase contrast, and reduce the background moonlight.  There is no discernible tail visually or in this photograph.  Longer exposures in a dark sky do show a faint ion tail.  Remember this is a short period comet, and has been around the Horn (perihelion) innumerable times.  It orbits the Sun from just inside Jupiter’s orbit to just outside Earth’s orbit every 5.4 years.

Happy comet hunting!

11/25/2018 – Ephemeris Extra – Comet 46P/Wirtanen may be naked eye in December

November 25, 2018 Comments off
Comet 46P/Wirtanen in December 2018
he path of Comet 46P/Wirtanen from November 21, 2018, to January 1, 2019. The labels are month, date, and expected magnitude. On November 22nd it was observed to be magnitude 5.5, about 5 magnitudes brighter than the predictions on the chart.  Click on image to enlarge. Created using Cartes du Ciel (Sky Charts).

Comet 46P/Wirtanen will be well placed in the evening sky for observation. Though a small comet, it has a history of being active, which is not disappointing us now. It will be closest to the Earth on December16th at 7.1 million miles (11.4 million km). 

On December 16th the comet will be closest to the Pleiades. On the 23rd it will appear close to the bright star Capella. After that it will become circumpolar.

Comet Wirtanen is a small short period comet of 5.44 years.  It’s orbit doesn’t come as close to the Sun as the Earth.  It’s closest to the Sun, called perihelion it which it reaches December 12th is about 98 million miles (158 million km).  The orbit extends out to nearly Jupiter’s orbit.

Checkout photos and animations of this and other comets in’s Realtime Comet Gallery.

Also check out Seiichi Yoshida’s website and his weekly information about Bright Comets:

Comet and the Pleiades
Here is a black on white chart that I created for our society’s newsletter of the positions of the comet when it passes the Pleiades.  The positions are for 9 p.m. EST (01:00 UT on next date) on the displayed dates. Created with Cartes du Ciel (Sky Charts).

A note about comet magnitudes

Comet magnitudes are always devilishly hard to estimate. A comet always appears dimmer than its magnitude suggests because one is comparing the brightness of a diffuse object with the point source of a star. One either has to reduce the size of the comet to almost a point or defocus the star to the size of the comet to make the comparison if it doesn’t have a tail.

A point about magnitudes. They’re like golf scores. The lower the number, the brighter the object, and the better the golf score. Blame the ancient Greek astronomer Hipparchus, who ranked star brightness from first magnitude for the brightest stars to sixth magnitude for the dimmest stars visible to the naked eye. Modern astronomers put a mathematical basis for the system saying that a magnitude difference of 5 equals a brightness difference of 100. So each magnitude step equals the 5th root of 100 or 2.512. So a 5thmagnitude star is about two and a half times brighter than a 6thmagnitude star, and so on.

10/04/2018 – Ephemeris Extra – Wintermaker rising

November 4, 2018 Comments off

A chill is in the air, The Fisher, Ojiig’s bloody tail has swooped low in the north at midnight to paint the trees with their fall colors, and the leaves have fallen to the ground. Haven’t heard of the Fisher? I mention it from time to time here on my Ephemeris program on Interlochen Public Radio. It’s a constellation of the Anishinaabe peoples indigenous to this area of Michigan, of which the Chippewa, Ottawa, and Ojibwe are a part.

The Fisher occupies the stars which we know as the Big Dipper and the Great Bear, Ursa Major. And unlike the bear, a fisher really does have a long tail. The fisher is a real weasel-like animal whose diet apparently does not include fish. It is found across southern Canada and in the American West. I’ve related the story of the Fisher, and how he brought summer to the Earth, in these pages in the August 2012 issue and on my blog Search for fisher. Like most legends, there are different versions of that story and others about the Fisher.
Fisher or not, summer is gone and the world seems darker and colder. Over in the east these evenings great winter constellation of Orion is rising. It brings to mind the Robert Frost poem Star-Splitter, and our star chart this month from the November 1st post:

“You know Orion always comes up sideways.
Throwing a leg up over our fence of mountains,
And rising on his hands, he looks in on me
Busy outdoors by lantern-light with something
I should have done by daylight, and indeed,
After the ground is frozen, I should have done
Before it froze, and a gust flings a handful
Of waste leaves at my smoky lantern chimney
To make fun of my way of doing things,
Or else fun of Orion's having caught me.
Has a man, I should like to ask, no rights
These forces are obliged to pay respect to?"

The rest of the poem is available on the Poetry Foundation website: The poem is about one Brad McLaughlin and his telescope. While I don’t approve of how he financed his telescope, I do share his enthusiasm.

North Hegman Lake Pictographs
North Hegman Lake Pictographs with the Wintermaker (Orion), Curly Tail (Leo-Hydra), and Moose (Pegasus). Credit: Etphonehome.

The Wintermaker, Biboonikeonini’s, name literally means North Wind. While his torso is the same as Orion’s his arms stretch from Aldebaran in Taurus to Procyon in Canis Minor, just about spanning the entire winter sky. The pictographs, seen above of the Wintermaker, Curly Tail and Moose can only be seen from a canoe in the cliff face on one side of the narrows between North Hegman and Trease lakes, 15 miles north of Ely, Minnesota

Wintermaker rising
The Wintermaker (Orion) rising in the east-southeast. And Hole-In-The-Sky (Pleiades) as seen in Stellarium with Ojibwe Star Lore in Stellarium. From the Ojibwe Sky Star Map Constellation Guide, ISBN 978-0-615-98678-4 by A. Lee, W. Wilson, and C. Gawboy.

In late winter as Ojiig is rising in the northeast signaling the maple sugaring season, the Wintermaker is moving lower in the southwest. Some Ojibwe parents make bows for their children to shoot arrows at the Wintermaker to convince him to flee the skies so spring can begin as a way to teach them the old legends of their culture.

The Pleiades is an important group of stars for the Anishinaabe in several ways. It is the Hole-In-The-Sky, Bagone’giizhig, through which the Sky Woman fell and to give birth to the first humans on the Earth.

The Pleiades also represent the seven poles of the Shaking Tent Ceremony, and the seven sacred stones that are heated for the sweat lodge, which is also seen in the stars in the spring as Corona Borealis.

They are also the Seven Daughters of the Moon and Sun. They loved to dance and play, and when their father, the Moon was low in the sky, would descend to the Earth in a basket to do their thing. On one of their trips to the earth, one of them was captured by a human and she ended up falling in love with him, and married him. When father Moon found out he permanently dimmed her star, so now most people now only can spot 6 of the stars. This last bit seems to parallel the Greek story of the lost Pleiad.

Note:  This is published as an article in the Grand Traverse Astronomical Society’s November 2018 newsletter Stellar Sentinel.