Globe Gets Less Gravity
By Anne-Marie Morgan
“…and the Weightwatching Nation of the Year goes to…Canada!!”
“Errr, how can that be with all those Maple syrup pancakes?” we wonder.
“Because gravity doesn’t weigh you down as much.”
Yes, it’s true, in parts of northern Canada gravity doesn’t pull you down to Earth as strongly as it does elsewhere, so you actually weigh less. However, before you run off to buy that flight with only a pair of Speedos or a polka dot bikini in your suitcase, you will only weigh 1/25,000th less. That’s a mere 0.1oz if you weigh eleven stone (150lb), which may not help a great deal when you step on the scales.
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Liverpool-based geophysicist Dr. Mark Tamisiea leads a team at the Harvard-Smithsonian Centre for Astrophysics. They suggest that the drop in gravity in two regions flanking Hudson Bay – Keewatin and northern Quebec – is due to events that occurred around 20,000 years ago.
Between c.90,000 and c.16,000 BC, large tracts of North America were covered by a 3km-deep glacier known as the Laurentide Ice Sheet. Thick domes of ice formed in areas where the gravitational pull is now reported to be less. The pressure exerted by their weight resulted in the bedrock becoming compressed and sinking – displacing the mantle underneath. As a result, the mass of the Earth is lower than average in these areas, so they exert less of a gravitational force. Dr. Tamisiea says that it may take up to 300,000 years for the regions’ gravity to return to normal.
Results from the GRACE satellites provide answers to many of the major scientific questions relating to climate change, allowing scientists to study the internal structure of the earth in great detail. For example, GRACE data will help scientists to understand how the mass of ice sheets are changing, and how that will impact on global sea levels. In turn, this could lead to a better understanding of the forces that cause El Niño and La Niña, as well as providing more accurate seasonal forecasts of the Earth’s weather patterns and of natural hazards.
Read more about the lighter side of science:
- Spoof - Toast, gravity and a malevolent God
- News - NASA to launch gravity tractor
- Strange - How shiny is Los Angeles?
- Gadgets - Buy an anti-gravity globe
