Bright light in the night sky: Supermoons or perigean moons

Moon studies
(courtesy NASA, Clementine trackers)

By Marie Powell

We've all heard stories about the full moon making people and animals behave in strange ways. When the moon is full, we can see the whole "face" of the moon for three or four days. According to legend, the full moon can cause werewolves to change shape, and people to go mad or commit more crimes.

The full moon caught the public's attention this summer in another way. Each year, we experience times when the earth and moon come close together in their orbits. Astronomers, or scientists who study the solar system and celestial bodies like the moon (astronomy), call the point at which the moon's orbit is closest to the earth the "perigee," while the point farthest away is the "apogee." During some months, the earth and moon come closer together in orbit. These "perigean" moons may look brighter and larger than usual.

Astrologers, or those who see relationships between astronomy and people, call these moons "supermoons." This term is credited to astrologer Richard Nolle and has become popular in the media. 

The first of three perigean full-moons in 2014 occurred on July 12. According to some sources, the centre of the moon and the centre of the earth were about 361,800 km (224,800 mi) apart. We will see this "supermoon" again on August 10 and September 9. 

The full moon has a different name each month in folklore, and the name varies depending on whether you live in the northern or southern hemisphere. For example, the July full moon is known in the northern hemisphere as the Buck Moon (when deer grow antlers), Thunder Moon, or Hay Moon. Here are two interesting sites that show the various names of the full moon:

Almanac Full Moon Names:

http://www.almanac.com/content/full-moon-names

Earthsky Full Moon Names (northern and southern hemispheres):

http://earthsky.org/astronomy-essentials/full-moon-names

For more information about the phases of the moon, check out these websites and articles:

Understanding Astronomy by Daniel V. Schroeder: 

http://physics.weber.edu/schroeder/ua/MoonAndEclipses.html

Lunar phases of the moon (photographs) by Anthony Ayiomamitis:

http://www.perseus.gr/Astro-Lunar-Scenes-Apo-Perigee.htm

Full moon calendars:

NASA (600 years of moon phases):
http://eclipse.gsfc.nasa.gov/phase/phasecat.html
(This year is included here: http://eclipse.gsfc.nasa.gov/phase/phases2001.html)

http://moongiant.com/Full_Moon_New_Moon_Calendar.php

http://www.moonconnection.com/moon-july-2014.phtml

For more information about the night sky, see Joan Marie Galat's "Observing the Night Sky" here on Sci/Why.

Marie Powell is the author of 15 books for children, including Dragonflies are Amazing (Scholastic Canada) and the Word Families series (Amicus Publishing).

Save the night

by Joan Marie Galat
Author of the Dot to Dot in the Sky books - blending astronomy with ancient mythology

While delivering astronomy presentations at schools in southern Alberta a few weeks ago, I took advantage of the opportunity to ask my elementary age audiences two simple questions. How many of you have heard of a supernova? How many have heard of a black hole? While I was surprised to see how many hands went up in the Kindergarten to grade three groups, I was not surprised to see their interest in the night sky.  Exploding stars are exciting! Black holes fill imaginations with "what if" questions.

Although exploding stars are rarely seen and black holes are invisible, there are many other objects in the night sky to enjoy. You can see the Andromeda Galaxy with the naked eye, as well as Mercury, Venus, Mars, Jupiter, Saturn, and the 88 official constellations.

Unfortunately not everyone can enjoy the celestial wonders that should be visible on a good dark night. Those living in brightly lit cities and towns face light pollution strong enough to make dim stars less visible, constellations difficult to identify, and dark sky objects impossible to see. Even those in rural communities may find their night sky lit by yard lights, traffic, and nearby communities.

You can help reduce light pollution in a number of ways:
-stop using lights to decorate outdoors
-never use more light than you need
- choose lower wattages whenever possible
-close curtains at night to prevent light from trespassing outdoors
-consider whether you can be more selective about when you use outdoor lighting
-ensure outdoor lighting only illuminates the area you need lit
-turn off lights when they are not needed
-encourage others to be aware of their use of lighting.

Discover more strategies to reduce light pollution from the International Dark-Sky Association.

Earth at night

Credit: NASA Earth Observatory/NOAA NGDC