Sunday, September 30, 2012

Why do Geese Fly in a V

The fall migration of birds is well underway.  In the meadow outside my home in NH, there are flocks of white-throats sparrows and juncos feeding on seeds and insects.  Also there is the lovely sound of geese overhead flying in formation towards the beaver pond down the hill.  Have you ever wondered why geese fly in a V-formation?  Migration uses up lots of precise energy.  By flying in a V, the flock is conserving energy.  How?  Each goose flies slightly above the one in front of it.  This cuts down on wind resistance because the flapping of the bird in front creates an uplifting draft of air making it easier for the bird behind it to fly.  The energy saved in flight can be as much as 50%.  Therefore the lead bird is working the hardest while the rest of the birds can glide more and use less energy.  When the lead bird tires, it will fall back in the formation to an easier flying position and another bird will take over the lead.  This way the flock shares the hardest work.  Also, this type of formation allows for the birds to keep track of each other.  This assists in the communication within the flock and its coordination.  Who are in the flocks? Usually they are individual or multiple family groups.  Research shows that geese families will stay together during migration and in their winter feeding grounds.  It isn't until the springtime when they return to their breeding grounds, that the yearlings will venture off on their own. Fun Fact:  A group of geese on the ground is a gaggle, but a flock in  the air is a skein.  Photo: - San Francisco

Friday, September 28, 2012

The DC Women's Hiking Group will hike Tues., Oct. 2nd and Thurs., Oct. 4th at Lake Windwing in  Ridgefield, across from Ridgebury Elementary School, off of South Shore Drive.
Meet at 8:30am in the parking area.

Monday, September 24, 2012

The DC Women's Hiking Group will hike Tues., Sept. 25th and Thurs., Sept. 27th at Saugatuck Falls Natural Area in Redding, CT.
Saugatuck Falls Natural Area entrance is located between mail box # 65 and 73 on Diamond Hill Road, Redding. Follow straight in until you see the large sign (entrance marker) on your left.
Meet at 8:30am.

Saturday, September 22, 2012

Autumnal Equinox

Today is the Autumnal (fall) Equinox.  Although most people hardly even notice it, the natural world is now speeding up the process of winter preparation.  The young of spring are now mature and for some learning their last lessons in survival.  The sun’s quickening demise is triggering the internal clocks for others to start heading southward.    Those that must stay are packing on the pounds in preparation for the lean months ahead.  Plants are reacting by sowing their seeds and green plants are decreasing chlorophyll production.  This will eventually lead to exposing the other colors that had been hidden by the green into the brilliant colors of fall.  For the farmers who still live by the seasons, it means the last harvest of the year.  
      Thanks to the earth’s 23.5° tilt, equinoxes occur twice a year – in March and September.  It is when day and night are nearly exactly the same length.  The word equinox is derived from Latin, meaning “equal night”.  However, to the casual observer, this doesn’t seem correct.   The day time seems longer than the 12 hours. There are two reasons for this.  First, sunrise and sunset times are calculated by the outer edge of the sun’s disk not the center.  So the disk is still in the sky after sunset occurs.  Second, the Earth’s atmosphere refracts light.  This gives the illusion that the sun is in the sky longer than it really is.  The Autumnal Equinox is the herald of winter.  If this depresses you, head to the southern hemisphere where today it is the Spring Equinox.  (Picture credit: Kimberly Achelis Hoggan)

Monday, September 17, 2012

The Discovery Center Women's Hiking Group will hike Tues., Sept. 18th and Thurs., Sept. 20th at
Scott Lot Preserve in Redding, CT.
Coming from the north on Route 7 turn left onto Old Redding Rd. Right after going under RR bear right onto Mountain Rd. Follow Mountain Rd. to end and turn left onto Peaceable St. Parking for the open space will be on the left. If you come to an electrical substation, you went too far. Meet at 8:30am.

Saturday, September 15, 2012

Sept. 2012 Constellation of the Month - Sagittarius

We can use our either our July constellation of the month -- the Summer Triangle --  or our August constellation -- Scorpius --  to find our September constellation of the month – Sagittarius.  The Summer Triangle points south to a spot just east of the teapot-shaped Sagittarius, which, in turn, is just east of Scorpius.  Sagittarius is easy to recognize, being compact in shape and comprised of moderately bright stars.

Sagittarius is unique in at least one respect: when you look in the direction of Sagittarius, you are looking toward the center of our Milky Way Galaxy.  Not surprisingly, the band of the Milky Way appears brightest in that direction.  

The center of our galaxy is about 27,000 light years from the Earth – or 27,000 times 6 trillion miles.  At the center is a super-huge black hole with a mass of about 4 million of our Suns.  It is constantly adding to its mass by sucking in everything which is "nearby" by astronomical standards, including stars, nebulae and other black holes.

Sagittarius has several nebulae and star clusters which can be seen in small telescopes, such as those we use in Discovery Center astronomy events.  The most famous of these are the spectacular Lagoon Nebula, Omega Nebula and Trifid Nebula.