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12/11/2018 – Ephemeris – The Chinese just launched a spacecraft to land on the far side of the Moon

December 11, 2018 Leave a comment

Ephemeris for Tuesday, December 11th. The Sun will rise at 8:10. It’ll be up for 8 hours and 52 minutes, setting at 5:02. The Moon, half way from new to first quarter, will set at 9:06 this evening.

Last Friday the Chinese launched their Chang’e 4 spacecraft to land on the far side of the Moon in January. That side of the Moon has been mistakenly called the dark side. It actually gets more sunlight than the near, Earth facing, side. This will be an extraordinary feat. So how can they tell what’s happening on the other side? In preparation for this landing attempt the Chinese put a communications relay satellite in a halo orbit about the Earth-Moon L2 Lagrange point 38 thousand miles (61 thousand km) beyond the Moon. It is a kind of a gravitational point of equilibrium behind the Moon. One of five, and they are very useful. The satellite will lazily orbit that point, in view of the lander and the Earth for continuous communication between the Earth and the lander.

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

Addendum

Chang'e 4 trajectory

Chinese mission to land a lander and rover on the far side of the Moon. Click on the image to enlarge.  It’s in Chinese except the numbers. Credit China Aerospace Science and Technology Corporation via Space.com.

How Queuiao, the lunar communications satellite orbiting L2 performs its relay function

How Queuiao, the lunar communications satellite orbiting L2 performs its relay function. Click on image to enlarge. Credit CNSA via gbtimes.com.

Note:  Next Monday’s program will be about Lagrangian points.

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11/23/2018 – Ephemeris – The Moon and Aldebaran

November 23, 2018 Comments off

Ephemeris for Friday, November 23rd. The Sun will rise at 7:50. It’ll be up for 9 hours and 17 minutes, setting at 5:07. The Moon, at full today, will rise at 5:55 this evening.

Tonight’s full Moon will be accompanied by the bright star Aldebaran, the angry red eye of the constellation Taurus the Bull. Earlier this year we had the last of nearly two years of the Moon every month passing in front of Aldebaran. The tilt of the Moon’s orbit with respect to the Earth’s own orbit of the Sun slides slowly westward with time, so The Moon won’t pass in front of Aldebaran for those of us on Earth again until 2033. This sliding of the Moon’s orbit is called regression of the nodes. A node is where the Moon’s orbital plane crosses the Earth’s. These are places eclipses of the Sun and Moon occur if lined up with the full or new moons. Why regression? The nodal points are moving westward, backward of most motions in the solar system.

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

Addendum

Full moon with Aldebaran
Tonight’s full moon with Aldebaran in the face of Taurus the bull (8 p.m. November 23, 2018). Created using Stellarium.

10/12/2018 – Ephemeris – The Moon’s phases

October 12, 2018 Comments off

Ephemeris for Friday, October 12th. The Sun will rise at 7:54. It’ll be up for 11 hours and 8 minutes, setting at 7:03. The Moon, halfway from new to first quarter, will set at 9:31 this evening.

The Moon’s changing appearance over the month may seem to be mysterious at first glance. Maybe because one may think that the objects in the sky are somehow different from the familiar objects we see around us on the Earth. In ancient times, especially the Greeks thought that everything in the heavens halfway perfect and spotless. They explained the definite markings we see as the man-in-the-moon as a reflection of the Earth by a spotless Moon. The Moon’s phases are simply light and shadow on a ball in the sunlight. Sometimes, when the Moon appears in the daytime, take a small ball, like a golf ball and hold it up to the Moon, while the ball is also in sunlight, and the small ball will exhibit the same phase as the Moon.

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

Addendum

Moon phases
One of the best explanation diagrams of the Moon’s phases as it relates to the Earth and Sun. Click on the image to enlarge. Credit Wikimedia user Orion 8.
Moon ball
Demonstration of the Moon’s crescent phase with the Styrofoam moon ball we use for Project Astro held up to a light off of the frame to the right. The night side of the ball is illuminated a bit by the translucency of the ball, and the reflection off of my hand. Note the roughness of the ball is visible only at the terminator.
Moonball
Demonstration of the Moon’s gibbous phase with the Styrofoam moon ball we use for Project Astro held up to a light off of the frame to the right. The night side of the ball is illuminated a bit by the translucency of the ball, and the reflection off of my hand. Note the roughness of the ball is visible only at the terminator.

09/25/2018 – Ephemeris – The harvest moon effect

September 25, 2018 Comments off

Ephemeris for Tuesday, September 25th. The Sun will rise at 7:33. It’ll be up for 12 hours and 1 minute, setting at 7:34. The Moon, 1 day past full, will rise at 8:17 this evening.

The full, or nearly full moon, just rising, looks like a large orange pumpkin. The color, like the red of the sunset is caused by the scattering out of blue light by the atmosphere. It can happen at any full moon, not just the Harvest Moon, which was officially yesterday. What the Moon around the Harvest Moon does do is rise only a little later each evening. This helped the farmers in earlier times extend daylight to bring in the crops. On average the moon rises or sets 50 minutes later each night. However when the Moon is in the part of the sky where it is moving northward as well as eastward, then it rises only a little later each night. Tomorrow’s Moon will rise only 27 minutes later than it will this evening.

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

Addendum

Harvest moon effect 2018
The harvest moon effect 2018 showing the shallow path of the Moon near moonrise and the intervals between them for 5 consecutive dates. Created using Cartes du Ciel (Sky Charts).

09/24/2018 – Ephemeris – The harvest moon and the Chinese Mid-Autumn Festival

September 24, 2018 Comments off

Ephemeris for Monday, September 24th. The Sun will rise at 7:32. It’ll be up for 12 hours and 4 minutes, setting at 7:36. The Moon, at full today, will rise at 7:51 this evening.

Tonight at 10:53 p.m. the Moon will be full. And since it’s only two days past the autumnal equinox, this makes it the Harvest Moon. This full moon also marks the Chinese Mid-Autumn Festival to honor the Moon and the story of Chang’e a mortal woman to took an elixir and flew off to the Moon and became a goddess. Another story revolves around the Jade Rabbit pounding Medicine. I talked about the figure of a rabbit seen on the face of the Moon last Monday. He is a companion to Chang’e, and has a mortar on the Moon with him. He pounds out the medicine that makes the inhabitants of the sky immortal. The Chinese lunar probes are named Chang’e. Chang’e 3 landed on the Moon in 2013 and sent out a lunar rover named Yutu , the Jade Rabbit.

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

Addendum

The Jade Rabbit
The Jade Rabbit on the Moon. The more complete title is Jade Rabbit pounding medicine (in the mortar at his feet.
Chang'e flying to the Moon
Chang’e flying to the Moon. Unknown source.

09/17/2018 – Ephemeris – The Moon Tonight and the Jade Rabbit

September 17, 2018 Comments off

Ephemeris for Monday, September 17th. The Sun will rise at 7:24. It’ll be up for 12 hours and 25 minutes, setting at 7:49. The Moon, 1 day past first quarter, will set at 1:03 tomorrow morning.

Now is a good time to point that small telescope or binoculars toward the Moon. The gray seas on the right side of the moon depict the neck, head and ears of the Jade Rabbit. It’s curled up body is on the night side of the Moon to the left. The rabbit is upside down as we see him with the naked eye or binoculars. The Sea of Serenity is the upper part of his body, the head is the Sea of Tranquility. A bay south of Tranquility and the Sea of Nectar is one ear and the Sea of Fertility is the other ear. The Jade Rabbit is related to the Chinese Mid-Autumn Festival which occurs at our Harvest Moon. It’s on September 24th this year. Another amateur astronomer and myself brought telescopes to the local festival last year to view the Jade Rabbit on the Moon.

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

Addendum

The Moon tonight
The Moon tonight, September 17, 208 at 9 p.m., with the head of the Jade Rabbit. Created using Virtual Moon Atlas
The Jade Rabbit
The Jade Rabbit on the Moon. The more complete title is Jade Rabbit pounding medicine (in the mortar at his feet.  From Wikipedia source is Zeimus.

09/13/2018 – Ephemeris – The Man in the Moon’s eye

September 13, 2018 Comments off

Ephemeris for Thursday, September 13th. The Sun will rise at 7:19. It’ll be up for 12 hours and 37 minutes, setting at 7:57. The Moon, 3 days before first quarter, will set at 10:27 this evening.

The Moon tonight is a 4 day old moon, and appears near the planet Jupiter. Day one is its first appearance in the evening after disappearing from the morning sky. The ancients called it the new moon, but astronomers treat the conjunction of the Moon and the Sun as the new moon. In this program I note the days before or after the nearest quarter phase, as a better representation of the actual appearance of the Moon’s phase. The Moon will be a beautiful crescent tonight. Binoculars will reveal a dark area just above the fattest part of the crescent. It serves as one of the Man in the Moon’s eyes. Its official name is Mare Crisium, or Sea of Crises. Most of the Moon’s seas are connected, or appear to be. This one is definitely not.

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

Addendum

The 4 day old Moon

The 4 day old Moon showing Mare Crisium, the Sea of Crises. 9 p.m. September 13, 2018. Created using Virtual Moon Atlas.

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