Archive for August, 2010

Where do comets come from?

Mathematical theory suggests that most comets may come to the solar system from very far away, as far away as 100,000 Astronomical Units. In this picture, the solar system is buried deep within the cloud.

An Astronomical Unit (or AU) is the distance from the earth to the sun and is equivalent to about 93,000,000 miles. Mars is 1.5 AU from the sun, Jupiter is 5 AU from the sun, and Pluto is 39 AU from the sun. So comets come from very far away indeed.

Comets are observed to come to the solar system from all directions, therefore the place where the comets come from is thought to be a giant sphere surrounding the solar system. This sphere is called the Oort cloud after Jan Oort who suggested its existence in 1950.

But some comets may come to the solar system from closer in. The place where these comets come from is called the Kuiper Belt, which is located past the orbit of Pluto. Source: the University Corporation for Atmospheric Research.

Find the latest astronomy and science toys here.

How long does it take food to digest?

As the average person’s stomach will hold less than two quarts, it only stays in this stage of the digestive process for three to five hours. The stomach slowly releases this semi-digested food to the intestines where it completes the digestive process. Roughly 15-17 hours after you take the first bite, the food is excreted as feces.

Some foods may pass quicker than this, depending on one’s specific reaction to a specific food. And some foods may stay in your system longer. Other variables affecting digestion time is one’s level of physical activity and even drugs taken subsequently (caffeine, nicotine, prescription drugs, etc.).

Posted by admin for best selling toys at Atomic Elephant Science and Toy Co. 

What is the world’s smallest mammal?

There has been some debate on this, depending on how you define an animal’s size. The Bumblebee Bat (Craseonycteris thonglongyai) is definitely the world’s smallest species of bat. It is about 30mm in length and weighs about 2 grams (less than an American penny). It is the only known species in its genus and is found in a tiny region of western Thailand, in the Sai Yok National Park, Kanchanaburi Province.

One of the more interesting notes is that the Bumblebee Bat was virtually unknown until 1974 when it was discovered by Kitti Thonglongya, a biologist in Thailand. Their habitat has been highly affected by deforestation and unsustainable levels of teak logging. In 1982, the Royal Forest Department of the Thailand Government only found 160 of them living in 3 caves, despite extensive surveys. Bumblebee bats are now considered one of the twelve most endangered species on the planet.

The other mammal in competition for the title of the “world’s smallest” is the Etruscan Pygmy Shrew (Suncus etruscus). This shrew weighs less than the Bumblebee Bat but the bat’s skull is shorter. [Wikipedia] The smallest mature specimens of this shrew are thought to weigh about 1.3 grams and measure 36 mm long. This small mammal is 60 mm from the tip of the nose to the base of the tail. This shrew has a lifespan of about 15 months and lives the forests and brush areas between Southern Asia and Southern Europe.

Sources: Portland State University,  Experience Festival.

How do snowflakes form?

Snowflakes are the result of symmetrical crystallization of water molecules as they turn into ice crystals. Water molecules, when pass to crystalline solid state, such as in ice and snow, form weak bonds (called hydrogen bonds) in which two hydrogen atoms tend to attract neighboring water molecules.

When the temperature drops below the freezing point, the water vapor molecules form hydrogen bonds into a solid state, which exhibits the lowest-energy, an open framework that has a basic symmetrical, hexagonal shape of the snowflake. The higher the symmetry, the more stable the crystal, because this maximizes attractive forces and minimizes the repulsive ones.

The crystallization process is like tiling a floor in accordance with a specific pattern: once the pattern is established and the first tiles are put in place, then all the others go in the predetermined pattern to maintain symmetry. Water molecules simply put themselves to fit the spaces and keep symmetry; this way, the different arms of the snowflake appear.

There are many different types of snowflakes (“no two snowflakes are alike”) because a differentiation occurs due to specific forming circumstances: atmospheric conditions, notably temperature and humidity; and in the atmosphere, where conditions are very complex and variable.

A crystal might begin to grow in one manner and then trasformations in temperature or humidity, after minutes or seconds, change the growth pattern. The hexagonal symmetry prevails, but the ice crystal may form a different branching pattern. The atmosphere changes take place over a large area, so the snowflakes in a region are alike.

Source: Softpedia.com.

How does squinting improve vision?

Under normal conditions, light comes into the eye in all directions. Rays coming in at an angle above or below the horizontal will naturally focus in front of or behind the center of vision. Rays coming in more directly would tend to focus more directly on the retina. By squinting, you create a smaller opening for incoming light – similar to how the aperture on a camera works. The narrower you can make this “aperture,” the more likely the light rays coming in will be closer to the horizontal Read more…

Why do all newborn babies have blue eyes?

At birth, the genes that make the pigment protein are not being read by the cell (they are turned off). Almost all babies have blue eyes because the iris has not yet made brown pigment (called melanin) that colors the iris.

As the child’s eyes are exposed to light (as they weren’t in the womb), the light then triggers the cell to start reading the gene. But it can take a while for the cell to ramp up to the final levels of pigment. That is why so many babies have blue eyes for their first months of life. Usually by their first birthday a baby’s eye color has settled in, but sometimes the iris doesn’t make enough melanin until about 3 years of age.

A nice description from About.com follows: “An infant’s eye color is determined by a substance called melanin. Melanin is a dark pigment contained in the iris, the structure that controls how much light is allowed into the eye. The color of the iris is determined by the amount of melanin in the iris. Light eyes have very little pigment, whereas darker eyes have a lot. In newborns, the pigmentation process of the iris is not yet complete. Babies with darker skin are usually born with dark eyes that stay relatively dark. Iris color in lighter-skinned babies is usually a blue or bluish-gray color at birth, then change as they grow. Melanin production changes during the first year of life, usually resulting in a darker, deeper eye color.”

Sources: Understanding Genetics at TheTech.org.

What is the world’s oldest dog?

While reliable information on this question is fairly hard to come by, there have been a few reliably substantiated cases of dogs living for almost 30 years.

The oldest dog that has been somewhat reliably documented was an Australian cattle-dog named Bluey. He is reported to have lived from June 7, 1910 to November 14, 1939 (29 years, 5 months and 7 days). Bluey was owned by Les and Esma Hall of Rochester, Victoria, Australia.

In September, 2008 another dog was reported to have died at over 29 years old. Bella, a Labrador mix was owned by David Richardson of Derbyshire, England. The Guinness Book of World Records reports the oldest dog (with reliable documentation) to be Butch, a 28-year old Beagle in America who died in 2003.  See the list of oldest dogs on record.

Bramble, the Labrador pictured above was reliably recorded to have lived over 27 years and died in Somerset, England in 2003. He currently has the position as the second oldest dog on record.

Sources: The World’s Oldest Dog Dies and Vegetable-Eating Dog Lives to Ripe Old Age of 27.