Ask The Science Experts

The dodo bird, or Raphus cucullatus, became completely extinct around 1800. While thousands of these birds were slaughtered for meat, it it generally believed that their demise was primarily due to pigs and monkeys eating their eggs.

The birds were native to the Mascarene Islands in the Central Indian Ocean. They became extince on Mauritius around 1680 and on Reunion Island about 1750. They remained on Rodriguez until 1800.

Source: The Handy Science Answer Book. Posted by admin for the science best selling toys of 2008.

The short answer is because of the nature of the ionosphere of the Earth. The ionosphere consists of several different layers of gases that have become conductive from the bombardment of the atoms by: solar radiation, by electrons and protons emitted by the sun, and by cosmic rays.

These layers, sometimes called the Kennelly-Heaviside layer, reflect AM radio signals, thus enabling AM broadcasts to be received by radios that are a long way from the transmitting station. At night, the ionosphere layers partially dissipate and become an excellent reflector of the short waveband AM radio waves.

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Source: The Handy Science Answer Book.

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.).

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You might think the animal with the longest gestation period would be one of the larger mammals, but in fact it is the Alpine black salamander. It is a viviparous amphibian which lives in the high altitude Swiss Alps. At altitudes above 4,600 feet, it’s gestation period can be up to 38 months. It bears two fully metamorphosed young.

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In short, a liquid’s boiling temperature is dependent on its composition and the atmospheric pressure on the boundary between the liquid and the air above it. For water, the boiling point at sea level is 100 degrees Celsius (212 degrees Fahrenheit). The atmospheric pressure is roughly 29 mmHg at sea level, but this number is dependent on altitude and is lower the higher you get from sea level.

Boiling is the process in which the molecules in a liquid have enough energy to overcome the opposing pressure of the atmosphere. When these liquid molecules start turning into gas molecules, we say the liquid is boiling. If you lower the opposing pressure, there will be less resistance to the water molecules turning into gas molecules and entering the air, and the liquid will boil at a lower temperature.

It follows that water would boil quicker on a day with lower atmospheric pressure than on a day with a higher pressure. This is true although the difference in barometric pressure on any given day at the same altitude isn’t as great as a change from differing altitudes.

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What does Doppler radar mean and how is it different from other radar?

RADAR, an acronym for Radio Detection and Ranging, operates by transmitting a wave and recording the time it takes that wave to bounce off of an object and return to the source. Since we know the speed the transmitted wave is traveling, we can calculate the distance of the object.

Doppler radar operates on the same principle, but it also detects an objects motion by measuring the frequency shift between the outgoing wave and the returning wave. An object moving toward the radar would increase the returning wave’s frequency while an object moving away from the radar decreases the wave’s frequency. For weather purposes, this provides important information about the speed and direction of winds within thunderstorms.

Source: USA Today, Ask the Weather Experts. Posted by admin for the best selling toys of 2008 at Atomic Elephant Science & Toy Co.

I saw a couple of good posts on this from astronomycafe.net on their ask the astronomer page. The general consensus of all the answers out there seems to be that we do not know exactly, but there are at least a hundred billion, and possibly several hundred billion. The following is quoted from Astronomy Cafe:

We do not know exactly. Within the part of the universe we can observe there seem to be at least 100 billion, but this could be an underestimate if you include dwarf galaxies that are too far away to be easily seen by even the Hubble Space Telescope.

Imagine looking at a dime about 75 feet away. The Hubble Space Telescope can represent this narrow “keyhole” stretching to the visible horizon of the universe.  This “deep field image” shows hundreds of galaxies in a region only an arcminute across. What is an arcminute? Take the diameter of the full moon, divide it by 30 and that’s about an arcminute. While this is a tiny tiny view of the visible universe, it can give scientists a way to extrapolate and estimate how many galaxies there may be.

Now, even more interesting, the following answer comes from Kathy Wollard’s “How Come?” book. Our galaxy, the Milky Way is an immense spiral galaxy with about 200 billion stars. This number of stars is almost unimaginable to us, but even more astounding is that each star is often trillions of miles from its nearest neighbor star. This is how big ONE galaxy can be. Current theories are that these huge galaxies are probably the result of tens or hundreds of smaller galaxies colliding and becoming one. Of course, a “collision” in this sense actually can take millions of years. The basis of this theory is that when astronomers look far out into space, more than 2 billion light years (which is also looking 2 billion years into the past), they see more small galaxies and fewer big ones.

Imagine this: the light we see coming from a galaxy 2 billion light years away, is 2 billion years old. This is just hard to comprehend.

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