QUESTION YOUR WORLD: Happy Halloween - priceless science

Hello boys and ghouls! Once again, the equinox has happened and daylight savings time has not ended yet, which means its time for Halloween!! Check out the video clip for some fun with Halloween numbers!

That's right $2 BILLION spent on candy each year for Halloween. What a sweet research project this was! For more information check out this link from the National Retail Federation, . They've studied up and surveyed a lot of information about what flies off the shelf around Halloween.

Also, all that candy means a lot of sugar in a lot of mouths! That's the tooth folks! Our teeth are pretty amazing actually. Check out some interesting facts on teeth for all of you that want to bite into this topic a bit more:

http://www.nhs.uk/Livewell/dentalhealth/Pages/Toothfacts.aspx


http://www.infobarrel.com/15_Facts_about_Teeth#axzz1bFadL861


http://library.thinkquest.org/J0112820/facts.html

Whoa! Sharks have about 40 sets of teeth in their lifetime? A Chinese dentist once built a tower out of 28,000 human teeth??
Chew on that for a while!

Lastly, be sure to spot an awesome science based costume this year!! They can be as simple as a scientist or as complex as an atom! .

Be safe and have fun out there! Happy Halloween from us here at the Science Museum of Virginia!

Is It Winter Yet? Maybe, Maybe Not…

Snow frozen onto a tree in Germany.
Photo courtesy of Wikipedia

Tuesday, December 21, is the Winter Solstice and usually considered the first day of winter. However, meteorological winter is already here! So what’s the deal? Well, the definition of winter depends on whom you ask.

A meteorologist defines winter as the three coldest months of the year: December, January and February. An astronomer defines winter as the three months between the Winter Solstice (December 21 or 22) and the Spring or Vernal Equinox (March 20 or 21). What’s the difference?

The definition of meteorological winter is fairly straightforward. Climatologically-speaking, the three coldest months of the year are December, January and February in the Northern Hemisphere. Therefore, meteorological winter begins on December 1 and ends on February 28 (or 29). In the Southern Hemisphere, the seasons are reversed, meaning if you lived in Rio or Buenos Aires, summer would begin in December and winter would begin in June.

Astronomical winter begins on the Winter Solstice, the shortest day of the year. The Earth has seasons and variable daylight hours because its axis is tilted 23.5° relative to its orbit around the sun. Winter in the Northern Hemisphere occurs when the northern half of the planet is tilted away from the sun. This tilt causes sun’s energy to be weaker on the Earth’s surface because:

• The sun shines on the Earth’s surface at an oblique angle.
• The sun’s energy is spread out over a larger area, diluting its strength. 
• The sun’s rays travel through more atmosphere before they reach the surface. 
• Days are shorter so there is less time for the sun to heat the surface. 

Less energy from the sun on the Earth’s surface means colder temperatures in the atmosphere – so winter arrives. For more information, check out last year’s blog about the Winter Solstice: http://sciencemuseumofvirginia.blogspot.com/2009/12/winter-solstice.html

Here are some questions for you to ponder:

• If the Earth’s axis had no tilt, would we have seasons? 
• If the tilt was at a greater angle, what would our seasons be like? 
• Do you think other planets in the solar system have seasons too? 
• How did Earth’s axis get tilted in the first place?

Good-bye, ospreys! See you next year...

If you spend much time on the Virginia coast, the high-pitched call of the osprey is a familiar sound. In fact it’s so familiar that it’s often taken for granted …until it’s gone. I love fall with its cool sunny days and blue, blue skies, but I am always a little sad when the ospreys leave. Around mid- September, the ospreys who summer on the Chesapeake Bay disappear. Where do they go?

Dr. Richard O. Bierregaard, Jr. knows! He has been studying ospreys for over 40 years. In 2000, in collaboration with Dr. Mark Martell, he began installing GPS tracking devices on young ospreys to track their migration patterns, including several from the Chesapeake Bay region. Ospreys have been tracked to winter quarters in the Caribbean, Central and South America, as far south as Peru! His tagged birds have names and his website is updated regularly with their progress. By September 12, three birds, Penelope, Sr. Bones and Thatch (Thatch is from Delaware) had begun the long and perilous journey south. Gunny left on September 19 and arrived in Virginia Beach on Tuesday. Other tagged birds, including Neale, Sanford and North Fork Bob, should be leaving soon. To follow their progress, go to: http://www.bioweb.uncc.edu/bierregaard/migration10.htm.  I have to admit that following these birds as they make their way south and, hopefully, back north again could become an addiction.

If they survive the journey and winter, they will return around mid-March to nest near the area where they were born. Ospreys begin mating at three years of age and will often mate for life. Nests consist of bulky piles of sticks on navigational markers, duck blinds, utility poles or high up in a pine tree, but always near the water. Females usually lay three eggs in mid-April to late May.  By July, the fledglings fly from the nest and begin to practice their steep dives to catch fish.

Ospreys are sometimes confused with bald eagles. It’s certainly easy to do – ospreys look remarkably similar to both juvenile and adult bald eagles. Here’s a brief primer to tell them apart: ospreys are dark brown or black with white underparts, a broad black eye stripe and a black patch on the underside of the wings. Adult bald eagles have white heads and tails but dark underparts, while juvenile bald eagles are all brown or mottled brown and white all over. Ospreys are slightly smaller than bald eagles and fly with their wings "crooked" in an M shape, whereas bald eagles fly with their wings in a flat line.

We are fortunate here in the Chesapeake Bay region to have the largest nesting population of ospreys in the world, over 2000 pairs which accounts for 25% of the US population. While they are wintering in warmer climes, I hope to follow the travels of Penelope, Sr. Bones, Thatch and Gunny and will eagerly await their return in the spring!

Winter Solstice *

At 12:47 pm today, December 21, 2009, winter begins in the Northern Hemisphere. The first day of winter is called the Winter Solstice; likewise, the first day of summer is the Summer Solstice. The word solstice is derived from Latin and means “sun standing still.” On these two days of the year, the sun’s apparent position in the sky has reached its most southern or northern extreme. Today there will only be 9 hours and 33 minutes of daylight in Richmond, but tomorrow the number of daylight hours will once again begin to increase.
The solstices and the seasons occur because the Earth’s axis is tilted 23.5° relative to its plane of revolution around the sun (see illustration). In the Northern Hemisphere winter, the northern half of the globe is tilted away from the sun; therefore, the sun is low in the sky giving us shorter days and longer nights. At this oblique angle, the sun’s energy is spread over a larger area of the Earth’s surface and thus is weaker than if it was hitting the surface more directly. Also, the sun’s rays must travel through more atmosphere before they reach the Earth’s surface, and some of the solar energy is reflected back into space. In addition, there are less daylight hours to warm the Earth. With all these factors combined, is it any wonder that we have winter weather?
Contrary to what many believe, the Earth is not farther from the sun during the winter. Actually, the Earth is almost at its closest point to the sun at the time of the northern hemisphere’s Winter Solstice. This variation in the Earth’s distance from the sun is small and does not greatly affect the weather; however it does slightly modify the severity of the Northern Hemisphere winters and summers.
While we are experiencing winter, the southern hemisphere is experiencing summer. Our Winter Solstice is the southern hemisphere’s Summer Solstice. If you lived in Rio or Sydney, the winter months would be June through August and the summer months would be December through February.
Here’s some food for thought: what if the Earth’s axis was not tilted? Would we have seasons? What if the axis was tilted more than 23.5°? Or less than 23.5°? What would our seasons be like? How did the Earth get its tilt? All the planets in our solar system have some axial tilt, but they are all different. Why?

*Technical difficulties delayed the posting of this blog entry.