Heavenly Errors
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"The more we have a scientific understanding of nature, the more we are able to make informed decisions in all aspects of our lives." - Neil Comins

In his latest book, Heavenly Errors: Misconceptions About the Real Nature of the Universe, University of Maine Professor of Physics and Astronomy Neil Comins explores the difference between reality and perception: the differences between how nature really works and our beliefs about how it works. Here are a few of the misconceptions about the cosmos he addresses:

Comet tails trail behind comets.
Comets have two tails and neither trails behind the comet nucleus of ice and rocky debris. The straight gas tail of a comet always points directly away from the sun. The curved dust tail always arcs between the gas tail and the direction from which the comet is coming.

The sun shines by burning gases.
Energy in the form of heat and light is released not by combustion, but by the fusion of 660 million tons of hydrogen per second to form helium. The sun contains no solid or liquid matter; it does not have a "surface," in the traditional sense.

The sun is a star that gives off yellow light.
The sun is an ordinary star among hundreds of billions in our galaxy. It actually gives off mostly turquoise light.

Stars twinkle.
Stars appear to twinkle because the Earth's atmosphere is not a uniform gas. By changing the direction of starlight moving through it, the ever-shifting atmosphere creates the impression that stars are twinkling.

Each point of light we see in the night sky is a single, isolated star.
Less than half of the objects we see at night are isolated stars. The rest are pairs or small clusters of stars orbiting each other.

Pluto is always farther from the sun than Neptune.
Pluto's orbit is so elongated that for about 20 years of its 249 Earth-year orbit around the sun, it is closer to the sun than Neptune. This occurred most recently between 1979 and 1999.

All the moons in our solar system are similar to ours: spherical, airless, with light and dark gray regions, and craters.
At least 84 moons are in our solar system, and fewer than 25 are spherical. The others look more like giant potatoes. Several have measurable atmospheres. Most have either a single hue of gray or a variety of colors, as well as surface features.