Monday, December 8, 2008

What's Up? - A new brightening source of pollution

Welcome back to What's Up?

During the last Athena Community Astronomy Club meeting one of our club members gave a presentation on light pollution. It's a very important issue and it must be brought to attention.

Light pollution is the brightening of the sky caused by excessive light being emitted from streetlights and other (mostly) man-made lighting. This has been a growing problem ever since the beginning of the industrial era.

Just by looking at a picture of the Earth taken at night (above image - NASA) it's easy to tell that a lot of light is shining upwards. Anyone who lives in or near a large city is very unaware of the many stars that are hidden by the bright city lights. Many people have never seen more than a handful of stars in their lifetimes and have never seen the beauty of the Milky Way.

Astronomers aren't the only ones that have a problem with light pollution. All this extra light can affect people's sleeping cycles and cause a loss of sleep. Medical research suggests that excessive light can cause an assortment of adverse health effects such as increased headache incidence, worker fatigue, increased levels of stress, increase anxiety, and possibly other unknown effects.

Animals are also affected by light pollution. It can confuse animal navigation, change relations between predator and prey, alter competitive interactions, and change animal physiology. Migrating birds can be confused by lights on tall building and other structures. The U.S. Fish and Wildlife Service have estimated that four to five million birds die per year because they are attracted to the lights. This can simply be prevented by turning out lights during migration periods.

When sea turtles hatch from eggs in nests on beaches they head away from the dark outline of dunes and vegetation. When there is artificial lighting they don't know which direction to move in and either die on the beach or get eaten by other animals. Baby seabirds can also be confused by lights as they move out of their nests and fly out to sea.

Lighting used to deter criminals from entering buildings are often enabling criminals. Inadequately placed lighting can remove shadows that would be cast by the criminal and create glare that can hide criminals from sight. Glare from streetlights can also be a hazard to motorists, bicyclists, and pedestrians.

All of this light that is pointed in any direction other than down is wasted. Over-illumination, the excessive use of light, is another cause of light pollution. The U.S. Department of Energy claims that about two million barrels of oil worth of energy are wasted every day (based on the U.S. consuming 50 million barrels of oil per day) because of over-illumination.

Prevention of light pollution can be very simple. Instead of installing incandescent or mercury-vapor bulbs that are currently very popular, low pressure sodium lights can be installed. Low pressure sodium lights are up to ten times more efficient than incandescent light bulbs and low pressure sodium lights are only directed downwards and are shielded so that no light escapes upwards. It also emits only one colour of light which is easy to remove from astronomer's images using computer software. By using less electricity there will be less pollution and money can be saved.

Better shielding (above right versus above left that has very little shielding) for other types of lights can be installed at anytime and can greatly reduce light pollution.

To learn more about light pollution on the web, go to Also check out Earth Hour at and learn more about this yearly event that raises awareness of light pollution and global warming.

While we can still see through the light pollution, lets take a look at what's up this month.

The moon will be full on Dec. 14 which will shrink to a new moon by Dec. 27.

Venus and Jupiter will be nearby each other low in the western horizon at the start of the month. Venus is the brilliant yellow star-like object. Jupiter is also brilliant but not quite as bright. They will be the two brightest objects in the night sky other than the moon. Moving further into the month, Venus will climb higher into the sky while Jupiter creeps lower and lower towards the horizon. They will be best viewed shortly after sunset.

Mercury will make a brief appearance near the end of the month. It will appear slightly below Jupiter in the western sky. Mercury will be best on Dec. 29 but can be viewed for a few days on either side of that date.

Mars will be heading near the sun and it will be hidden during the month.

At the same time Saturn will be rising in the night sky at about 1 a.m. Saturn will be a dull yellow colour and won't be anything special to look at with the naked eye. If you have the opportunity to use a telescope it will be an entirely different story. The rings will be close to being edge-on to our line of sight. They will appear like a thin golden band around this gaseous planet. By early September 2009 the rings will be perfectly edge-on for the first time in 14 years and disappear from sight since they are so thin.

Until next month, just look up!

Hey Kids...

Last month a large space rock flew into the Earth's atmosphere and exploded! This was a very special event because most space rocks are just pebble sized. They burn up in the atmosphere and create a little trail as they burn up – you may know these as shooting stars. This big space rock is guessed to have weighed 10 tons! It may sound huge but most of it burned up on the way down. A few small pieces have been found in Saskatchewan near a little pond. This may have been the brightest shooting star in Canada in the last 10 years and was completely unexpected. Keep looking up, you never know what you may see!

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