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08/28/2014 – Ephemeris – The evening Moon will stay low in the sky for the next couple of weeks.

August 28, 2014 Comments off

Ephemeris for Thursday, August 28th.  The sun will rise at 7:00.  It’ll be up for 13 hours and 25 minutes, setting at 8:26.   The moon, 3 days past new, will set at 9:40 this evening.

Since we’re within a month of the autumnal equinox, coming up on September 22nd, something funny is happening with the Moon rise and set times near both new and full moon.  That is they aren’t changing very much.  Here we are with the Moon three days old, and it still sets before the end of astronomical twilight.  You may notice that for the next two weeks, that the Moon doesn’t get very high in the sky in the early evening.  It’s path stays close to the horizon.  Around first quarter next Tuesday the Moon will get to be just a little higher in the sky than the sun does on the first day of winter.  The next full moon is the Harvest Moon, being the full moon closest to the first day of autumn.  Then the day-to-day succession of rise times again will slow.

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

Addendum

Low Moon

The Moon on September 3, 2014 a day after first quarter. It will rise higher after that if one stays up long enough. Created using Stellarium.  Click on image to enlarge.

In the image above the Moon’s orbit is compared to the ecliptic, the plane of the Earth’s orbit to which it’s inclined by about 5º.  Note the two points where these lines cross.  The point where the Moon’s orbit crosses the ecliptic heading northward is called the ascending node.  The crossing point heading southward is the descending node.  The important thing about that is the when the moon passes a node while at new or full, an eclipse will occur,  which they will do in October.  There will be a total lunar eclipse on the morning of October 8th, then a partial solar eclipse on October 23rd as the sun is setting here in northern Michigan.  I’ll have more information as the events gets closer.

01/06/2014 – Ephemeris – It will be a year of eclipses for northern Michigan!

January 6, 2014 1 comment

Ephemeris for Monday, January 6th.  The sun will rise at 8:19.  It’ll be up for 8 hours and 58 minutes, setting at 5:18.   The moon, 1 day before first quarter, will set at 12:07 tomorrow morning.

The year 2014 will be a year of eclipses.  World wide it will have the minimal number of eclipses possible, four.  However, lucky us, we will see three of them if it’s clear, that is.  The first is a total eclipse of the moon in the wee morning of Tax Day, April 15th.  It will be the best of the three because we will see it from beginning to end.  On October 8th we will have another lunar eclipse is the morning.  This one will start closer to dawn, so the kids can see this one by getting up early.  The total phase will be visible, but the moon will set as the moon is leaving the earth’s shadow.  The last will be a partial solar eclipse on October 23rd. when the eclipse will be interrupted by sunset.

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

Addendum

My Article in January’s Stellar Sentinel, the newsletter of the Grand Traverse Astronomical Society.

After a drought in visible eclipses seen from our part of the planet last year and a single partial solar eclipse the year before, we have a chance, weather permitting, to view two total lunar eclipses and the first half of a partial solar eclipse this year. OK, we did have a penumbral lunar eclipse last year, but I usually don’t count penumbral eclipses, since the casual observer may look at the moon and not know they are occurring.  They’re what I call a 5 o’clock shadow eclipse, where parts of the moon are illuminated by a partially blocked sun.  There is no obvious dragon or Cookie Monster nibbling at the moon.

Eclipse Seasons

In 2014 the two eclipse seasons are in April and again in October.  These are about six months apart centered around the moon’s ascending and descending nodes, where the plane of the Moon’s orbit crosses the Earth’s orbital plane when the new moon’s shadow can fall upon the earth and the earth’s shadow can fall on the full moon.
The line of nodes regresses westward or clockwise slowly in an 18.6 year period.  That means that the eclipse seasons slowly move backward through the calendar.  Every time the sun passes a node there are either two or rarely, three eclipses.  Either one each of lunar and solar separated by two weeks from the other.  Or, rarely, a central eclipse with 2 weeks before and two weeks later a very partial eclipse near the poles in the case of solar eclipses or penumbral eclipses in the case of lunar eclipses.  2014 is a year of two total lunar eclipses and two partial solar eclipses near the poles.

Saros

A means of predicting eclipses was developed by the Chaldeans in what is now Iraq some centuries before the common era (BC or BCE).  The Greeks learned of it.  Hipparchus and Ptolemy knew of it.  Solar and lunar eclipses repeat every 18 years 11 1/3 days.  This cycle was called the Saros by Sir Edmund Halley of Halley’s Comet fame, then Astronomer Royal in England.
The saros is the near coincidence of 3 lunar “months”:  the Synodic Month, or lunation the period between new moons; the Draconic Month, the period between the moon’s passage of the ascending node of its orbit as explained above; and the Anomalistic Month, the period between passages of the moon through perigee, the closest point in its orbit to the earth.
The synodic month is on average 29.530589 days, and the basis for the Jewish and Islamic lunar calendars.
The draconic month is 27.212220 days long on average.  The ascending node regresses westward, so meets the moon, traveling eastward than the synodic month, where it has to catch up with the eastward moving sun.  Remember the dragon eating the sun image from above. The ancients thought a dragon lived at the nodes to devour the Sun or Moon in eclipses.  The symbol for the ascending node:DragonsHeadis called the Dragon’s Head. For the descending node the symbol is inverted and called the Dragon’s Tail. These symbols may be seen on orbital diagrams.
The anomalistic month is 27.554551 days.  In celestial mechanics an anomaly doesn’t means anything is wrong, it’s the angle between, in the case of the moon, the perigee of its orbit and the position of the moon as seen from the earth.  It has to do with the perigee and that’s why it’s used.
It turns out that:
223 Synodic Months = 6585.322 days
242 Draconic Months = 6585.8 days
239 Anomalistic months = 6585.5 days
Thus the Saros cycle is 6585.322 days long, or 18 years 11 1/3 days, meaning that the next eclipse of that Saros occurs a third of the earth in longitude west of the previous eclipse.  It takes three saros cycles for an eclipse to repeat near the same longitude.  For instance, my first total solar eclipse was viewed from Quebec on July 20, 1963. The third Saros of that eclipse will occur on August 21, 2017.  I expect to be around to see that, my 5th total solar eclipse.  The path will shift southward and be seen across the continental United States.
There are something like 40 Saros cycles active at one time.  Eclipses at the descending node head southward each eclipse, while those at the ascending node move northward.

The Eclipses of 2014

Here are the dates of the eclipses:
Total Lunar Eclipse April 15, 2014
Total Lunar Eclipse October 8, 2014
Partial Solar Eclipse October 23, 2014
Interestingly, all these eclipses will occur in the western part of the sky for us in northern Michigan.  Both October eclipses will end with the eclipsed body setting before the official end of the eclipse.  This means that both lunar eclipses are early morning eclipses and the solar eclipse will be a late afternoon eclipse.
Lunar eclipses start and end with the moon traveling through the earth’s penumbral shadow.  It’s been my experience that this shadow only becomes visible in the half hour before and after the partial phases of the eclipse. The partial phase of the Tuesday April 15th lunar eclipse will start at 1:58 a.m., totality starts at 3:06 and ends at 4:24; with the partial phase ending at 5:33 as twilight begins to brighten.
The Wednesday October 8th lunar eclipse will start later in the morning.  The partial phase will start at 5:14 a.m. Totality will run from 6:25 to 7:24 a.m. all in the growing morning twilight.  Sunrise and moonset will interrupt the eclipse by 7:57.
The partial solar eclipse is on Thursday October 23.  The eclipse will begin around 5:33 p.m. for Traverse City with sunset at 6:44.  Times and whether the eclipse is visible at all depend on the location of the observer.

NASA diagrams, maps, and more information on these eclipses can be found here.

12/27/2012 – Ephemeris – That was the year that was.

December 27, 2012 Comments off

Ephemeris for Thursday, December 27th.  The sun will rise at 8:18.  It’ll be up for 8 hours and 50 minutes, setting at 5:09.   The moon, 1 day before full, will set at 8:10 tomorrow morning.

The end of the year is the perfect time to look back at the astronomical events of the year.  There was a partial solar eclipse in May and the rare transit of Venus across the sun in June.  You’ll have to wait until 2117 for the next one.  In July came news that the Large Hadron Collider had detected something that sure looked like the long sought Higgs Boson.  August brought the spectacular landing of the Mars Science laboratory, aka: The Curiosity rover, on Mars to begin an at least one martian year exploration.  In September the Dawn spacecraft bid farewell to the asteroid Vesta after a year exploring that remarkable asteroid, cranking up its ion engine for a three year journey to the dwarf planet Ceres.  The satellites Ebb and Flow completed their mission to map the moon’s interior.

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

Addendum

Hinode Views the 2012 Venus Transit

Hinode Views the 2012 Venus Transit. Credit: JAXA/NASA/Lockheed Martin

Simulated Higgs event

An example of simulated data modeled for the CMS particle detector on the Large Hadron Collider (LHC) at CERN. Here, following a collision of two protons, a Higgs boson is produced which decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue. Credit CERN.

Curiosity rover self portrait.

Curiosity rover self portrait. Credit: NASA/JPL-Caltech/Malin Space Science Systems

Vesta as Dawn headed off to Ceres.

Looking back at Vesta as Dawn headed off to Ceres. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

The Grail Spacecraft Ebb and Flow

The Grail Spacecraft Ebb and Flow made the most detailed gravitational map of the moon to map its interior; orbiting as close as 15 miles above the surface. They were intentionally crashed into a crater wall on December 17th. Artist conception credit: NASA.

11/13/2012 – Ephemeris – Total Solar Eclipse in the South Pacific

November 13, 2012 Comments off

Ephemeris for Tuesday, November 13th.  The sun will rise at 7:37.  It’ll be up for 9 hours and 39 minutes, setting at 5:16.  The moon is new today, and won’t be visible.

There will be a total solar eclipse today for the South Pacific Ocean.  The path of totality crosses almost no land except in the two northernmost tips of Australia.  Australia, New Guinea, New Zealand parts of Antarctica, Chile and Argentina will get a partial eclipse.  The moon’s shadow crosses the earth from west to east, so in crossing the International Date Line it will start at sunrise on November 14th local time and end at sunset November 13th local time.  The solar eclipse we’re waiting for is the total solar eclipse of August 21st 2017, now less than 5 years away.  This will be at least partial for the contiguous 48 states with the path of totality crossing the central United States.  Being in the path of totality that day is high on my bucket list.

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

Addendum

Diagram of the coverage of the November 13-14 total Solar Eclipse.  Courtesy Fred Espanek, NASA.

Diagram of the coverage of the November 13-14 total Solar Eclipse. Courtesy Fred Espanek, NASA.

Here’s an animation that brings the above chart to life.

November 13-14 total solar eclipse animation.  Courtesy NASA, A. T. Sinclair.

November 13-14 total solar eclipse animation. Courtesy NASA, A. T. Sinclair.

Our May 20th, 2012 solar eclipse experiences

May 21, 2012 1 comment

We knew seeing the eclipse would be a close thing.  We members of the Grand Traverse Astronomical Society had a full day of events.  It started with a full day at Northwestern Michigan College at their annual fund raising Barbecue.  Gary and Eileen Carlisle, Ron and Jan Uthe, Richard Kuschell, and myself had telescopes aimed at the sun.  Joe Brooks our meteor man was holding forth in one of the classrooms with his meteorite collection.  This went from 10 a.m. setup to 5 p.m. take down.

I immediately headed 30 miles westward to the Sleeping Bear Dunes National Lakeshore, and Pierce Stocking Scenic Drive and the Lake Michigan Overlook and our planned eclipse viewing party with the park rangers.  The rest of our group except Joe followed a bit later.  The sky was milky all day, and we had puffy clouds in Traverse City at the barbecue.  Watching the cloud animations on weatherunderground.com gave me some hope that the cloud bank we knew was over Wisconsin might just hold off so we could get the major part of what we projected would be the first 50 minutes of the eclipse before sunset.  There was also a spear of thunderstorms coming northward up the lake from the south.  The sky was so milky that we had no idea how high the cloud bank we knew was there actually was.

When I arrived at the entrance to the scenic drive the rangers told me that they may change our location due to blowing sand.  When I got to the overlook the sand was indeed being blown by gusts of wind coming from the southwest.

Lake Michigan Overlook Looking South

Lake Michigan Overlook Looking South

The above picture is from my scouting trip the week before.  We set up near that dune, which sheltered us pretty well from the wind.  However when I got home, I was full of sand, especially my hair.

It wasn’t until about 10 minutes before the start of the eclipse that the cloud bank was revealed.  It then was a race between the moon and the cloud bank.  The moon won by about 5 minutes.  My old friend John Russell, a professional photographer, was there and has posted an eclipse image on his Facebook page.

About 10 minutes later we found that the clouds were getting ugly, and approaching rapidly.

Looking in vain for the sun.

Looking in vain for the sun.  Isn’t that a thunderhead on the left?

That was it for the eclipse.  The rangers counted about 200 people who attended.

Gary Carlisle with binoculars and Richard Kuschel look for Venus above the cloud bank.

Gary Carlisle with binoculars and Richard Kuschell look for Venus above the cloud bank.

Gary Carlisle, who has a knack for finding planets in twilight, spotted Venus above the cloud bank and pointed his Celestron 8 telescope toward it.  Richard Kuschell located it too with his 4″ refractor to give the folks remaining a bonus view of the thin crescent of Venus.

We then packed up and headed back home with lightning to the south and a smattering of rain.

05/17/2012 – Ephemeris – A safe way to view this Sunday’s solar eclipse

May 17, 2012 Comments off

Ephemeris for Thursday, May 17th.  Today the sun will be up for 14 hours and 54 minutes, setting at 9:06.   The moon, 3 days before new, will rise at 4:44 tomorrow morning.  Tomorrow the sun will rise at 6:10.

Lets talk about a safe viewing method for viewing the sun, for Sunday’s solar eclipse, which starts about 8:19 p.m.  Never look directly at the sun, eclipse or no.  Pinhole projection is a cool method to watch the eclipse without hurting your eyes.  Get a cardboard box, the longer the better.  On one narrow end poke a hole, no larger than an 8th of an inch in diameter.  You can poke several holes an inch apart of varying sizes to get multiple images of the sun of different brightnesses and sharpness.  On the inside of the other end paste a piece of white paper.  Point the holey end at the sun and its image will be projected on the white sheet.  Tomorrow I’ll tell you where to go to get the best view of the eclipse.

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

Addendum

There’s more information on my blog here.

Pinhole projection:

Pinhole Projection of the sun.

Pinhole Projection of the sun.

Note the brightness of the sun was augmented and moon shadow added to give an idea what the solar image would look like.  The box is 39 inches long.  it gives an image 1/3 of an inch in diameter.

05/15/2012 – Ephemeris – Viewing prospects of Sunday’s solar eclipse viewed from northern lower Michigan

May 15, 2012 Comments off

Ephemeris for Tuesday, May 15th.  Today the sun will be up for 14 hours and 50 minutes, setting at 9:04.   The moon, 3 days past last quarter, will rise at 3:51 tomorrow morning.  Tomorrow the sun will rise at 6:13.

Sunday evening’s partial eclipse will begin within a minute of 8:19 p.m. for most locations in the IPR listening area.  The sun will be only about a 7 degree angle above the horizon at that time.  That’s slightly less than the width of your fist held at arm’s length.  At sunset, at about 9:10 p.m., with the flat horizon of Lake Michigan about 50% of the sun will be covered.  The farther inland you are, or east from the shore, the start of the eclipse will be about the same time, but sunset will be earlier one minute every 12 miles east you are.  An obstructed horizon will make sunset earlier.  Thursday and Friday I’ll have safe eclipse observing tips.  Or go to my May 8th entry at bobmoler.wordpress.com for an illustrated entry.

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

Addendum

May 20, 2012 eclipse from northern Michigan just before sunset. Created using Stellarium.

May 20, 2012 eclipse from northern Michigan just before sunset. Created using Stellarium.

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