What’s Up: December 2020

December offers the longest nights of the year for stargazing and there are many things to look for. The longest night (and shortest day) occurs at the Winter Solstice, which is on December 21.

Before discussing the stargazing opportunities in December, however, I first need to give answers to the November quiz. The first question I asked concerned the name of the full Moon that occurred on November 30. The name given to this Moon is the Beaver Moon. This is the time of the year when beavers are most active because they are busy building winter shelters. Many of the names for the full Moon come from Native Americans who kept track of the seasons by giving distinctive names to each moon. The Beaver Moon, for example, was the time to trap beavers to provide furs for the winter. The December Full Moon, which occurs on December 29, is known as the Cold Moon (for obvious reasons!).

The second question I posed in November was what the penumbral eclipse on November 29 would look like.

Lunar eclipses occur when Earth's shadow blocks the Sun's light that would otherwise reflect off the Moon. The Earth casts two shadows that fall on the Moon during a lunar eclipse. These shadows are known as the umbra and the penumbra (see diagram above). The umbra is the fully shaded inner region of a shadow, whereas the penumbra is a partial outer shadow. When the complete moon passes through the umbra there is a total lunar eclipse. If the moon just passes through the penumbra, then a penumbral eclipse occurs, which is less noticeable to an observer on Earth. The word umbra is a Latin word meaning shade, whereas penumbra means almost shadow. The next total lunar eclipse we will be able to see in Oregon will be on May 26 next year.

The image above of a penumbral lunar eclipse comes from an article in the BBC’s Sky at Night Magazine. The article (https://tinyurl.com/y4utrn34) offers excellent advice on how to observe and photograph a lunar eclipse.

The Geminid Meteor shower occurs in December and is one of the best showers of the year. The peak occurs on December 13 and 14 when some 120 meteors per hour are possible. The new Moon is on December 14 and so observers will have a nice dark sky to view the Geminids. The best way to see them is by looking toward the constellation of Gemini. Gemini is easy to spot in the western sky and is to the left of Orion. Its two brightest stars, Castor and Pollux, represent the mythological twin brothers of Helen of Troy. NASA has more information on the Geminids, which can be found at https://tinyurl.com/y4b3jyg2.

As I mentioned at the beginning of this blog post, the Winter Solstice occurs on December 21. The word solstice comes from the Latin words sol (sun) and sistere (to stand still). During the solstice, the Sun appears at its lowest point in the sky and it stays that way at noon (hence stand still) for a few days. Following the solstice, the Sun starts to appear higher in sky. Many cultures believe the solstice to be a rebirth of the Sun as the hours of daylight become longer (source: Farmers’ Almanac – https://tinyurl.com/y3a5vvhn). At the Solstice, your noontime shadow will be the longest of the year – check it out!

One of the most exciting events in December occurs on December 21 when Jupiter and Saturn appear closer in the sky than at any time since the year 1226. The image below (from Sky at Night Magazine) illustrates how the two planets appear to gradually move toward each other in the December sky. More information about this planetary alignment can be found on the Science Alert website at https://tinyurl.com/yynls5td.

NASA has some great coloring pages for Jupiter and Saturn. These can be found at https://tinyurl.com/yxofou2p. 

That's it for this month. See you next year!

What's Up: November 2020

The end of Fall and the beginning of Winter is a great time to go out in the evening and look at the night sky. The Sun is now beginning to set in the early evening (around 5PM on November 1), which means you can go out well before bedtime and before it gets too cold. In this blog each month I will discuss what to look for in the evening sky. My focus will be on things to look for that do not require expensive equipment. Most of the time the objects I will discuss can be seen by the naked eye or using a pair of binoculars.

Most amateur astronomers with telescopes prefer to examine the night sky when the sky is dark and the Moon is not too bright. The Moon, however, is a fascinating object to look at as it waxes (gets brighter) and wanes (gets dimmer) through its roughly 29-day cycle. Each of the eight phases in this cycle has a name: New, Waxing Crescent, First Quarter, Waxing Gibbous, Full, Waning Gibbous, Last Quarter, Waning Crescent.

In November, the New Moon will be on November 14 and the Full Moon will be on November 30. Usually there is only one Full Moon in any given month, but occasionally (about once every 2 or 3 years) there are two. This happened in October when a Full Moon occurred on October 1 and on October 31. When a second one occurs in a month is sometimes called a “Blue Moon.” You may have heard of the phrase “once in a blue moon,” which means something that occurs only rarely. You may find it interesting to research the origin of this phrase, which is more than 400 years old.

The Full Moon each month is usually given a name, which reflects the changing seasons and nature. For example, the one in October is called the “Hunter’s Moon.” Each month in this blog I will provide some challenges and projects that you may be interested in doing. The first challenge this month is to find out the name for the full Moon in November and why it has this name. Answer next month.

When people look at the Moon they often imagine they can see people or shapes. A second challenge for this month is to go out when the Moon is full or nearly full and find: “Man in the Moon”, “Woman in the Moon” and “Rabbit in the Moon.”

NASA has an extensive amount of information on the Moon at its moon.nasa.gov website. There are two interesting projects that NASA created that you may be interested in doing this month. The first is to keep an observation log of the Moon’s phases during November. A blank log can be found at: https://tinyurl.com/y226zec2

A second project is to cutout and assemble a Moon phase calendar. The calendar can be found at: https://tinyurl.com/y4c3p7zj

The last few months has been a great time to view three bright planets in the evening sky: Mars, Jupiter and Saturn. In October, Mars came closer to Earth than it will be for another 15 years. Mars will still be very bright in November and will be viewable all evening. It is easy to spot as it is bright and very red. Jupiter and Saturn will also appear as bright evening stars in November. On November 1, Jupiter sets at 9:32PM and Saturn at 9:57 PM. At the end of November, Jupiter sets at 8:02PM and Saturn at 8:14PM. If you have a pair of binoculars you can use them to see the rings of Saturn and the Galilean moons of Jupiter. 

There are many websites that help you find the planets in the evening sky. This one is easy to use (just click on the planet you are interested in): https://tinyurl.com/y4g8n6zd

        

Meteor shows are also fun to watch. In November, the Leonid shower peaks on November 16 and 17. You can expect to see about 20 meteors per hour. To spot them it is best to face north-east or roughly where the Big Dipper is located.

That is about all for this month. One last challenge. There is a Penumbral Lunar Eclipse on November 29. It will last for over four hours. The challenge is to find out what such an eclipse looks like. Answer next month.