Moon on the move
FRIDAY OCTOBER 02, 2009
The moon also varies monthly in distance away from Earth. Between 1750 – 2125 the closest (perigee) was 4th January 1912; and the most distant (apogee) will be 3rd February 2125. In speeds, the moon is cruising past us at 3000kph, towards or away at 150kph, eastwards through space around Earth at 60kph and crossing latitudes at 19kph. Perigee is not always over the same area but changes Earth hemispheres on an 8.85 year cycle. Perigee was last over the equator between 2006-7 and is in 2008 north of the equator.
When perigee is over the equator and the sun close to equinox, we get an increase in tropical cyclones, for instance perigee was equatorial between Feb 1988 and Nov 1989 and Cyclone Bola struck NZ on 7 March, 1988. On April 10, 1968, Cyclone Giselle brought flooding and destructive winds to most of New Zealand and the inter-island ferry Wahine sank in Wellington Harbour with the loss of 51 lives. Perigee, 2 days prior, was over equator between 1966 - 1968. On Xmas Eve 1974, Cyclone Tracy blew away Darwin and perigee was over equator 1974-5. The most destructive storm to hit New Zealand in the 20th century was when a depression crossed the North Island on 2nd/3rd February 1936 bringing widespread heavy rain, causing every major river in the North Island to flood. The Mangakahia River in Northland rose 19 metres, and from July 1935 to April 1936 perigees had been nearer the equator.
This happens every 4th year. As perigee creeps north, so does cyclonic activity and tropical cyclones get to be called hurricanes. New Orleans Hurricane Katrina, struck on Aug 29, 2005. That day the moon was 28degN. New Orleans is 29degN. Cyclone Nagris struck Burma on perigee of 6th of May. Moon latitude was 22N. Myanmar(Burma) sits at latitude 22N. Perigee will continue heading north until April and May of 2009. By mid 2010 perigee will again be nearer the equator and NZ will again be at risk. By 2011 cyclonic activity is expected to pick up again.
This year the first weeks of May, June and July had close perigees. May perigee was on 6th. We saw Nagris on 6th, then on 12th the Sichuan earthquake in China, registering 7.8 on the Richter scale, killing 70,000. The moon was still north of the equator, as is China.
The next perigee came on 4th June along the 26deg latitude line. Gigantic rains swept across the USA June 7-July 1 and the American Midwest flooded, affecting Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, and Wisconsin.
The next perigee was 2 July, 27degN. Tropical cyclone Bertha spawned on 3 July at around 24degN.
Until November 2008 perigees will be less powerful. This should result in lighter spring wind systems and greater chance of precipitation reaching the ground rather than being blown away. Therefore the curse of wind chill may not in 2008 affect lambing.
(Bertha source: http://www.gdacs.org/reports.asp?eventType=TC&ID=BERTHA&system=asgard&alertlevel=Green&glide_no=&location=)