Archive

Posts Tagged ‘First quarter’

02/19/2021 – Ephemeris – Let’s look at the first quarter Moon tonight

February 19, 2021 Comments off

This is Ephemeris for Friday, February 19th. Today the Sun will be up for 10 hours and 40 minutes, setting at 6:17, and it will rise tomorrow at 7:34. The Moon, at first quarter today, will set at 2:32 tomorrow morning.

I love a first quarter Moon. The terminator or sunrise line cuts the Moon in half. Lots of craters are easily seen due to the long shadows cast by their crater walls. Best seen in a small telescope or strong pair of binoculars is a three crater chain just below left of the center of the Moon. The top and largest crater is Ptolemaeus. Below and connected to it is Alphonsus. A bit below Alphonsus is Arzachel. Alphonsus is the interesting one. In the pre-Apollo days amateur and some professional astronomers saw glows or mists in Alphonsus. In 1958 a Russian astronomer obtained spectra of one such mist. In 1965 the last Ranger mission to impact the Moon was sent to Alphonsus, but it didn’t find anything unusual.

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

Addendum

The first quarter Moon tonight at 8 pm, February 19, 2021, as it might be seen in binoculars. Created using Stellarium.

First Quarter Moon

A telescopic like view of the Moon via the Virtual Moon Atlas pointing out the craters discussed in the text.

Ranger image 1

Ranger 9 Image of Alphonsus #1. Credit NASA/JPL.

Ranger Program

Left: The Ranger spacecraft. Right: The floor of the crater Alphonsus form Ranger 9. Only the last 3 spacecraft were successful. They transmitted images all the way down as they crashed into the Moon. Credit NASA/JPL.

12/18/2015 – Ephemeris – The Moon at first quarter tonight

December 18, 2015 Comments off

Ephemeris for Friday, December 18th.  The Sun will rise at 8:15.  It’ll be up for 8 hours and 48 minutes, setting at 5:03.   The Moon, at first quarter today, will set at 1:17 tomorrow morning.

By the time we see the moon tonight it will be at least 8 hours since the Moon passed the first quarter point and it’s terminator or sunrise line will appear slightly bowed.   This time, since I can only point out a few features at a time, I’d like to point out three craters on the upper, north portion of the moon.  They may be too small for binoculars, but fine for small telescopes.  They make a nearly right triangle in Mare Imbrium, the Sea of Showers near the terminator.  The largest is Archimedes, named for the 3rd century BC Greek mathematician, and inventor.  The northern crater is Aristillus, named after a 3rd century BC astronomer, The other crater is Autolycus, named for a 4th century BC Greek astronomer.

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

Addendum

First quarter Moon.

The first quarter Moon on December 18 at 9 p.m. EST. Highlighted are the trio of craters of which Archimedes is the largest. Created using Virtual Moon Atlas.

Other features visible are the crater Plato, the Alpine Valley, the crater Alphonsus, which I’ve covered in the past.  Search on them for their location and more information.

 

09/02/2014 – Ephemeris – Viewing the first quarter Moon

September 2, 2014 Comments off

Ephemeris for Tuesday, September 2nd.  The sun will rise at 7:06.  It’ll be up for 13 hours and 11 minutes, setting at 8:17.   The moon, at first quarter today, will set at 12:52 tomorrow morning.

Tonight on the moon there are some very prominent craters on the terminator or sunrise line that’s cutting the moon in half.  From the top or north of the moon there’s Plato, which is also called a ringed plain because it has a flat floor.  South of there is Eratosthenes, at the end of the arc of the Apennines mountain chain.  At the south or bottom end of the moon are two other of my favorite craters.    First is the crater Tycho, that doesn’t look spectacular now, but will when the Moon is full with its rays of ejecta crossing a long way across the face of the moon.  A little bit farther south, partially entering sunlight is the large crater Clavius.  On my blog, bobmoler.wordpress.com, I’ll illustrate what the Moon’s image looks like in different types of telescopes.

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

Addenda

The moon tonight

The Moon tonight at 9 p.m. (September, 2, 2014). Created using Virtual Moon Atlas.

Image orientation in telescopes

The orientation of what one sees in an astronomical telescope depends on the type of telescope and the placement of the eyepiece.  The orientations shown are for observers in the northern hemisphere.  For the images below the moon shown is due south.

Erect image

The orientation of the Moon as seen with the naked eye, binoculars, spotting scopes and telescopes with an erecting eyepiece.

Mirror image

The orientation of the Moon as seen in a refractor or a Schmidt-Cassigrain or similar type reflector with a diagonal at the eyepiece end, and the eyepiece pointing up. This is a mirror image due to an odd number of mirror reflections in the telescope.

Inverted mirror image

The orientation of the Moon as seen with a refractor or Schmidt-Cassigrain and diagonal with the eyepiece oriented horizontally. It is a n inverted mirror image.

Inverted Moon

The orientation of the moon through a Newtonian reflector or a refractor without an eyepiece diagonal. It is an inverted image, an image rotated 180 degrees.

For southern hemisphere observers for these images to work the moon would be due north and all the images would have to be upside down.

Correction 09/02/2014 11:07 p.m.

All images created using Virtual Moon Atlas.

 

04/18/2013 – Ephemeris – The moon at first quarter

April 18, 2013 1 comment

Ephemeris for Thursday, April 18th.  The sun rises at 6:52.  It’ll be up for 13 hours and 38 minutes, setting at 8:31.   The moon, at first quarter today, will set at 3:21 tomorrow morning.

Lets take a look at the moon tonight.  It’ll be about 6 hours after first quarter and we’ll see features at the terminator, the sunrise line that cuts the moon in half.  In small telescopes, at the north or top end of the moon, the wide flat  crater Plato is just entering sunlight.  Long shadows from its crater walls will retreat across its flat floor over the evening. If you look closely you’ll notice that the floor of Plato is slightly convex to conform with the curvature of the moon itself.  Nearby is the straight gash in the Alps Mountains, called the Alpine Valley.  Supposedly the crater Plato formed shortly after Mare Imbrium formed throwing up the Alps and the Apennine mountains to the south.  The Straight wall, can be seen on the south end of the moon.

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

Addendum

First quarter moon April 18, 2013

First quarter moon April 18, 2013 Created using Virtual Moon Atlas

Categories: Observing, Phases, The Moon Tags: ,

04/11/11 – Ephemeris – First quarter moon

April 11, 2011 Comments off

Monday, April 11th.  The sun will rise at 7:05.  It’ll be up for 13 hours and 16 minutes, setting at 8:22.   The moon, at first quarter today, will set at 3:45 tomorrow morning.

Lets take a look at the moon tonight.  It’ll be about 14 hours after first quarter and we see features at the terminator, the sunrise line that cuts the moon in half.  In small telescopes, at the north or top end of the moon, the wide flat  crater Plato has just entered sunlight.  Long shadows from its crater walls will retreat across its flat floor. If you look closely you’ll notice that the floor of Plato is slightly convex to conform with the curvature of the moon itself.  Nearby is the straight gash in the Alps Mountains, called the Alpine Valley.  Supposedly the crater Plato formed shortly after Mare Imbrium formed throwing up the Alps and the Apennine mountains to the south.  The Straight wall, another straight feature can be seen on the south end of the moon.

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

 

Addendum

 

First quarter moon April 11, 2011

First quarter moon April 11, 2011 Created using Virtual Moon Atlas