21 concepts: Astronomical factoids to have at your fingertips

Andromeda: When our sister galaxy’s one trillion stars collide with us in four billion years, no stars will make contact and nothing bad will happen. (NASA/JPL-Caltech)

Some people know a couple of outstanding facts about many diverse subjects. Possessing such proficiency, they’re shielded from ever being regarded as oblivious.

In that same vein, here are some critical astro-nuggets for easy memorization. If you can retain just one essential concept about every famous celestial object, you’ll never be entirely in the dark when it comes to the universe.


If someone were to say “Sun,” it would be great to know it’s so big, a million Earths could fit inside it. As an alternative, here’s a fascinating basic concept: The Sun’s energy is fierce enough to blow away pieces of itself – broken bits of its atoms that continually whiz past our world at 200 miles per second. This is called the solar wind.

Mercury: The smallest planet was very nearly destroyed by an asteroid impact, creating a huge circular scar called the Caloris Basin.

Venus: With sulfuric acid clouds, a surface pressure 50 times greater than a pressure cooker and a temperature of 900 degrees Fahrenheit, it’s the most hostile planet in the known universe.

Earth: Thanks to the Moon’s tides, our spin is slowing, making each day 1/700th of a second longer per century.

Mars: Its most unfriendly feature is its lack of air. The barely-there carbon dioxide at its surface is less than one-tenth the thickness as the air atop Mount Everest.

Jupiter: It’s all gas. Even down below, there’s no surface on which to land.

Saturn: Its gorgeous rings are countless chunks of ice whose dimension of 100,000 miles by a quarter-mile are analogous to a sheet of paper the size of a city block.

Uranus: This greenest body in the universe is dimly visible to the naked eye.

Neptune: With a synchronicity boasting one-second accuracy, Neptune orbits the Sun three times just as Pluto orbits twice.

Pluto: Being only two-thirds the size of our Moon, it would fit between here and Kansas.

The Moon: Its dozen dark blotches – the only features easily seen by the naked eye – are solidified lava long thought to be water. Each is named for either an emotion (Sea of Tranquility) or a weather phenomenon (Sea of Clouds).

The Milky Way: Our home galaxy was believed to be the entire universe until a century ago.

Andromeda: When our sister galaxy’s one trillion stars collide with us in four billion years, no stars will make contact and nothing bad will happen.

Black hole: The opposite of a hole or gap, it’s where matter is so crushed and packed, spacetime completely warps so its own light cannot escape.

White dwarfs: Common sunlike stars in their old age, after their own gravity makes them collapse to become 5,000 times denser than steel.

First-magnitude stars: The night’s 20 brightest stars, whose names (Arcturus, Vega, Sirius et cetera) are familiar around the world.

Cosmic rays: Broken bits of high-speed atoms that arrive here from all directions, zooming in from the rest of the universe.

Comet: Typically, a 20-mile ice chunk that partially turns to vapor when near the Sun, to produce a thin million-mile tail.

Asteroid: A rocky or metallic body two to 600 miles wide that orbits the Sun in the same flat plane and direction as the planets.

Meteor: Any celestial object zooming through our air and glowing from the heat. Mostly pieces of comets or asteroids.

Space: The largely empty medium of the universe, which has anti-gravity properties over long distances.

Want to know more? To read Bob’s previous columns, click here. Check out Bob’s podcast, Astounding Universe, co-hosted by Pulse of the Planet’s Jim Metzner.

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