ScienceIQ.com

Eratosthenes Measured Earth’s Circumference—Centuries Before Columbus Sailed

Eratosthenes (c. 276 – 194 BC) was born more than 2200 years ago in the Greek city of Cyrene, now a city in the North African country of Libya. (The Greek Empire surrounded much of the Mediterranean Sea and included present day Greece, Turkey, the Middle East, and regions of northern Africa.) As a teen, Eratosthenes (air-uh-TOS-thuh-neez) was sent ...

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EratosthenesEarthCircumference
Medicine

What is Headache?

When a person has a headache, several areas of the head can hurt, including a network of nerves that extends over the scalp and certain nerves in the face, mouth, and throat. The muscles of the head ... Continue reading

WhatisHeadache
Chemistry

What is Oxidation?

The term 'oxidation' derives from the ancient observation of rust (oxide) formation. Early chemists could determine an increase in the weight of a metal as it apparently captured something from the ... Continue reading

WhatisOxidation
Biology

Obesity: How much fat can your genes handle?

According to some experts, the popular formula for weight loss, 'eat less, and exercise more,' is not working for many Americans. Recent estimates say that about 34% of adults and 22% of preschool ... Continue reading

Obesity
Biology

We Live In Two Distinct Visual Worlds

Have you ever wondered what it would be like to live on a planet where all the colors were different from what you're used to? Actually, you already have a lot of experience with two different worlds ... Continue reading

VisualWorlds

Your Own Personal Rainbow?

RainbowsDid you know that no two people ever see the very same rainbow? It's true. Rainbows are formed when light enters a water droplet, reflects once inside the droplet, and is reflected back to our eyes dispersed into the visible spectrum; red, orange, yellow, green, blue, indigo and violet. The rainbow you are seeing is actually from water droplets positioned like a cone exactly 42 degrees from the line of light, with your eyes positioned at the tip of the cone. In other words, if the sun is near setting on the horizon and a rainbow occurs, you can look 42 degrees upward with the sun at your back, and the rainbow will be located in that position.

Considering that only the raindrops positioned at the surface of a cone with you at its tip can form the rainbow you are seeing, then two people standing side-by-side are observing rainbows formed by different sets of raindrops: each person has his or her own personal rainbow! And don't try to photograph your own personal rainbow in its entirety; it's too big to fit in the picture! It doesn't matter if the rainbow is formed from a garden hose or rain because a normal 35mm camera lens only has a field of view of 40 degrees. A rainbow's angular span is bigger than that. You'll have to buy a special lens.