Science is an imaginative adventure of the mind seeking truth in a world of mystery.
Sir Cyril Herman Hinshelwood

Thursday, December 22, 2011

NASA Cosmic Ornament

Cosmic Ornament

Pulsar SXP 1062

With the holiday season in full swing, a new image from an assembly of telescopes reveals a pulsar that appears like a spinning cosmic ornament. Combined data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton were used in the discovery of a young pulsar in the remains of a supernova located in the Small Magellanic Cloud, or SMC. This is the first time a pulsar, which is a spinning, ultra-dense star, has been found in a supernova remnant in the SMC, a small satellite galaxy to the Milky Way.

In this composite image, X-rays from Chandra and XMM-Newton have been colored blue and optical data from the Cerro Tololo Inter-American Observatory in Chile are colored red and green. The pulsar, known as SXP 1062, is the bright white source located on the right-hand side of the image in the middle of the diffuse blue emission inside a red shell. The diffuse X-rays and optical shell are both evidence of a supernova remnant surrounding the pulsar. The optical data also displays spectacular formations of gas and dust in a star-forming region on the left side of the image.

SXP 1062 interests astronomers because the Chandra and XMM-Newton data show that it is rotating unusually slowly -- about once every 18 minutes. (In contrast, some pulsars are found to revolve multiple times per second, including most newly born pulsars.) This relatively leisurely pace of SXP 1062 makes it one of the slowest rotating X-ray pulsars in the SMC.

Scientists have estimated that the supernova remnant around SXP 1062 is between 10,000 and 40,000 years old, as it appears in the image. This means that the pulsar is very young, from an astronomical perspective, since it was presumably formed in the same explosion that produced the supernova remnant. Therefore, assuming that it was born with rapid spin, it is a mystery why SXP 1062 has been able to slow down by so much, so quickly. Work has already begun on theoretical models to understand the evolution of this unusual object.

Wednesday, December 21, 2011

The Physics of Santa

I hope this makes you laugh a little.
Santa and sleigh

Santa at Nearly the Speed of Light

by Arnold Pompos, Purdue University, and Sharon Butler, Office of Public Affairs

About this time of year, inquisitive children of a certain age begin to question whether Santa is real. After all, Santa has a major delivery problem. There are some 2 billion children in the world expecting Christmas presents. Assuming an average of 2.5 children per household, then, Santa has to visit about 800 million homes scattered about the globe.

The distance Santa has to travel can be estimated from the following. First, while the surface area of Earth is about 1014 square meters, only about 30 percent of that is land mass, or about 0.3 x 1014 square meters. Second, we’ll assume, for simplicity’s sake, that the 800 million homes are equally distributed on this land mass. Dividing 0.3 x 1014 by 800 million gives 4 x 104 square meters occupied by every household (about six football fields); the square root of that is the distance between households, about 200 meters. Multiply this by the 800 million households to get the distance Santa must travel on Christmas Eve to deliver all the children’s gifts: 160 million kilometers, farther than the distance from here to the sun.

Thanks to the rotation of the earth, Santa has more time than children might initially think. Standing on the International Date Line, moving from east to west and crossing different time zones, Santa has not just 10 hours to deliver his presents (from 8 p.m., when children go to bed, until 6 a.m., when they wake up), but an extra 24 hours— 34 hours in all.

Even so, Santa’s task is daunting.

Now, some have guessed that Santa accomplishes his task by traveling at a speed close to that of light—let’s say, 99.999999 percent of the speed of light. By traveling that fast, in fact, Santa can deliver all his presents in just 500 seconds or so, with plenty of time left over (the remainder of the 34 hours) to polish off the cookies the children have left him on their kitchen tables.

There are certain consequences, however, of Santa’s traveling at this frantic pace. For example:
First, children may not be able to see Santa racing across the dark night sky, but they may be able to see a trail of light caused by Cerenkov radiation, a phenomenon created when charged objects travel faster than the speed of light (which they can do in transparent media, but not in a vacuum). Since the basic component of our atmosphere is nitrogen, light is slowed to 99.97 percent of its usual speed of 300,000 kilometers per second. Santa travels faster than this and undoubtedly is charged; as a consequence, then, he will emit visible photons. (Unfortunately, that light will be obscured by the light caused by the friction created when Santa rushes through the atmosphere. Also, Santa might roast in all this heat, but we’ll presume that Santa’s sleigh, like space capsules, has special protective shielding.)

Second, children will notice that as Rudolph, Santa’s lead reindeer, is rushing toward their homes, his nose is no longer red. The color depends on just how fast Rudolph is moving, turning yellow, then green, then blue, then violet, and finally turning invisible in the ultraviolet range as he accelerates to higher and higher speeds. This change in color is a well-known phenomenon, called the Doppler shift, which astronomers take advantage of to figure out the speeds with which the stars and galaxies in our expanding universe are moving with respect to us; from that information, the distances to these celestial objects can be deduced. Using the accompanying table, children can determine how fast Rudolph is traveling by noting the color of his nose.
One worry Santa has is whether, with his irremediable girth, he’ll be able to squeeze into all those chimneys. Traveling at nearly the speed of light makes the problem worse, because Santa gains mass (his kinetic energy adds to his mass, as Einstein’s famous E = mc2 attests). Children believe that Santa will easily fit in the chimney, because from their frame of reference, even though Santa is heavier, he has contracted. From Santa’s frame of reference, though, the chimney is narrower than Santa is.
But children need not fear. The theory of relativity assures us that Santa will fit (see figure 4), and their packages will be delivered on time.

Children might also wonder why Santa never seems to age. From year to year, he retains his cherub face and merry laugh, his long white beard and his round belly that jiggles like a bowlfull of jelly. The fact is that for objects traveling at close to the speed of light, time slows down. So, the more packages Santa delivers, the more he’ll travel, and the more he’ll remain the same, carrying on the Christmas tradition for generations of children to come.

Color of Rudolph’s nose: RedYellowGreenBlueViolet
Corresponding wavelength  
(in nanometers):
650   580   550   480   400  
Santa’s speed as a percentage  
of the speed of light (v/c)*:

Can Santa fit in the chimney if he’s traveling at nearly the speed of light?

To answer that question, we need to talk about two frames of reference: Santa’s and ours. We also need to place two periodically blinking lights, A and B, on the sides of the chimney. These lights will help us and Santa find the edges of the chimney in the darkness and therefore will determine when Santa is right above the chimney, ready to slide in. For Santa to fit into the chimney, his right and left sides need to be between lights A and B when they blink.
Santa1Figure 1: If Santa is traveling at normal earthbound speeds, say, 100 km per hour, he sees lights A and B blink at the same time. Just as his left arm touches A, his right arm also touches B; therefore Santa fits in (since Santa is not bigger than the chimney).
Santa2Figure 2: If Santa is moving at close to the speed of light, the situation changes. From our frame of reference, according to Einstein’s theory of relativity, Santa’s width contracts and he is narrower than the chimney. Therefore Santa has plenty of space to slide in.
Santa3Figure 3: From Santa’s frame of reference, however, the chimney is moving backward and is, in fact, narrower than he is. If Santa were to see A and B blinking at the same time, the chimney would be too narrow for him.
Santa4Figure 4: Not to worry. From Santa’s frame of reference, the two lights are not blinking at the same time. As light A blinks, Santa’s left side slips into the chimney. The chimney keeps moving backward as Santa’s body squeezes in, until finally, when light B blinks, Santa’s right side is perfectly aligned with the side of the chimney. Now all of Santa is in.

NASA Snow Globe

A "Real" Snow Globe
Click the link to see an animation of snow fall from February 2000 to November 2011.

These snow cover maps are made from observations collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.

Snow Cover

Monday, December 19, 2011

Rare Albino Hummingbird

15-year-old Marlin Shank photographed this extremely rare albino ruby-throated hummingbird in a park in Staunton, Virginia. See more pictures here, and read an interview with the photographer here.

Sunday, December 18, 2011

Big Cat Week

Big Cats Initiative 
National Geographic is working to avert the extinction of lions, tigers, and other big cats with the Big Cats Initiative, a comprehensive program that supports innovative projects. Learn how you can help save these animals. Check out their website to take action by learning more and donating.

Photo: Close-up of an African lion

African Lion

Photograph by Chris Johns
Fiercely protective of their prides, or family units, male lions patrol a vast territory normally covering about 100 square miles (260 square kilometers).

Photo: Bengal tiger with cub 

Bengal Tiger and Cub

Photograph by Michael Nichols
A mother Bengal tiger and her cub rest in the tall grass of a meadow. Tiger cubs remain with their mothers for two to three years before dispersing to find their own territory.
Photo: A female African cheetah and her three cubs

Cheetah Mother and Cubs

Photograph by Chris Johns
Cheetah mothers typically give birth to a litter of three cubs, all of which will stay with her for one and a half to two years before venturing off on their own. When interacting with her cubs, cheetah mothers purr, just like domestic cats.

First Step: Halting Decline of Lions and Cheetahs

Lions are dying off rapidly across Africa. These cats once ranged across the continent and into Syria, Israel, Iraq, Pakistan, Iran, and even northwest India; 2,000 years ago more than a million lions roamed the Earth. Since the 1940s, when lions numbered an estimated 400,000, lion populations have blinked out across the continent. Now they may total as few as 20,000 animals. Scientists connect the drastic decreases in many cases to burgeoning human populations. The Big Cats Initiative aims to halt lion population declines by the year 2015 and to restore populations to sustainable levels.

Animal Art

Photography by Mark Laita
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