Looking Up column: Blue moon, upside down moon
The moon is blue this Saturday night, Oct. 31.
One of the explanations for the phrase “once in a blue moon” is the rarity of having a second full moon in the same month. Full moon occurred Oct. 1, and is occurring again on Oct. 31. Still, the moon is far from the color blue no matter how many times it is full, so it still is an oddity.
The moon high in the night sky looks very white to our eyes; as it rises or sets, it looks some shade of red or orange, an atmospheric effect as seen in the rising or setting sun.
During a total lunar eclipse, the moon turns some shade of red, caused by sunlight from sunrises and sunsets passing around the Earth into the Earth’s shadow and dimly lighting the moon.
Close-ups of the lunar surface, were as seen by the Apollo astronauts and numerous unmanned spacecraft, show the actual color of the regolith (“soil”) to be some shade of gray.
They can call it blue all they want, as long as they show me pictures of the moon the correct way. Here I go again on my soapbox.
Many a time on a TV program or movie, the moon will be shown in the night sky, mirror-image (reversed), upside down or even worse, at an angle never seen from Earth.
Very often, a photograph of the moon is shown that was taken by a passing or orbiting spacecraft, depicting a side of the moon no human eyes had ever seen until the crew of Apollo 8 went into lunar orbit in December 1968.
It must be artistic license at best, or ignorance at worst, but another common mistake seen on TV or the movies - as well as in cartoons and other illustrations - is the night time crescent moon at an impossible angle - like pointing up.
Even worse than that is an illustration of the crescent moon with a star within the crescent shape. That would only be possible if the moon was physically shaped something like a banana rather than a sphere, partly lit so only a crescent shines in direct sunlight back at us. The rest of the moon is there, but dimmer, shining only in faint reflected light from the Earth’s shiny face.
If you ever do see what looks like a momentary star on the darkened portion of the moon, let me know! Amateur astronomers have viewed with a telescope or photographed rare flashes of light on the darkened moon, the light caused by a meteor strike.
Sorry to sound so fussy but it would not take much to show the moon correctly. Showing the moon in a wrong way does little to educate the public. Of course, at least they are showing what is supposed to be the moon.
Interestingly, there are times you will see the moon upside down from the way you are accustomed, or tipped at a strange angle. Just take a trip north or south. The farther you go, the more the moon’s orientation will shift. The same happens with the constellations.
The more you are rounding the Earth, the more you will see the perspective change. I have never done this, but if you visited the Southern Hemisphere, the moon and the constellations will be completely turned over.
That must be quite a sight. Have any of you experienced this? Have you ever seen the sky from Alaska or northern Canada?
You don’t have to travel very far to realize you are indeed on a round Earth. I look for it every chance I have to venture south, as far as Florida. I have also visited Haiti (in the tropics but north of the equator), where the sky’s changing perspective was the most dramatic I have ever witnessed.
If you are used to seeing the winter evening constellation Orion with the bright red star Betelgeuse at upper left, imagine seeing it from Down Under. Orion appears upside down, with Betelgeuse at lower right.
Small refractor telescopes typically give you a reverse-image when you look through it. They even sell reverse-image maps of the moon for use with these telescopes.
That is the view you would have looking in a mirror. In fact, you are looking in a mirror; the light path in the telescope is reflected off the “diagonal mirror” placed just below the eyepiece, which allows you a more comfortable view. There is a 45-degree angled, flat mirror or pentaprism in the diagonal, bending the light 90 degrees as it comes to focus in the eyepiece.
Without this, you would be looking through the telescope at a very awkward angle when pointing it anywhere up in the sky from the horizon.
There is a simple remedy to this. You can purchase a correct-image diagonal, which has not one but two flat mirrors, or an Amici roof prism positioned behind the eyepiece. The second mirror corrects the reverse view.
Enjoy bright red Mars in the east the next clear evening; Saturn and Jupiter in the west-southwest (Jupiter being the brighter); and, in the morning eastern sky, the brilliant planet Venus.
Keep looking up at the sky!
Peter Becker is managing editor at The News Eagle in Hawley, Pennsylvania. Notes are welcome at email@example.com. Please mention in what newspaper or website you read this column.