BRI member Jessica Vineyard contributed this illuminating piece on some astronomical basics. Perfect for reading by flashlight when you're out at night stargazing.

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WHY DO STARS TWINKLE?
Have you ever tried to figure out whether something is a star or a planet by looking at the light shining from them? The easiest way to tell the difference is that stars twinkle, planets do not.

Why is this true? It's fairly simple, actually. Stars are so far away that the light from a single star - even the nearest ones (besides the sun) - takes years to get to your eye. By that time, the beam of starlight that enters your eye is actually a delicate filament of light, easily affected by the ripples in the atmosphere.The rippling effect of the air around us is what makes the star appear to twinkle.

Planets, on the other hand, are much closer to us. In binoculars, or even with the unaided eye, you can actually see the round discs of planets. This light is from such a large, nearby source that it's not as easily affected by the turbulence in our atmosphere. Planets appear to have a strong, steady beam of light.

If you're not sure whether you're looking at a star or a planet, compare your target object with another source of light nearby. See if either of them twinkle. ★

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WHY ARE STARS MEASURED IN LIGHT-YEARS?
A light year is the distance light travels in a year. How far is that? Well, light moves at 186,000 miles a second (it's the fastest thing in the universe), and there are 31,536,000 seconds in a year. So the equation is: 186,000 (miles) x 31,560,000 (seconds)

That comes out to about 6 trillion miles. Stars are incredibly far away. Our galaxy, for example, is more than 100,000 light years across. It's a heck of a lot easier to refer to their distances in terms of light years than any smaller measurement. ☆

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WHY ARE STARS DIFFERENT COLORS?
A star's color usually indicates it's temperature. Generally speaking, blue stars are the hottest. The coolest are often red... and very large (called "red giants" because at the end of their lives, stars simultaneously cool off and swell up to 100 times their normal size). In between blue and red, in decreasing order, are white, yellow, & orange. ✮

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WHAT ARE SHOOTING STARS?
Meteors.
Okay, then - what are meteors?

Meteors are often the byproduct of comets, especially when they're in "meteor showers."

Explanation: When a comet passes near the sun, it leaves particles of rock and dust in its wake, called meteoroids. If the Earth passes near or through this trail of comet debris, some meteoroids are pulled toward us by gravity. They may get so close that they pass into our atmosphere - which quickly slows them down. (A lot like throwing a small rock into a pond of water.) We see a streak of light in the night's sky, caused by vaporization of the meteoroid's particles. And that's when the meteoroid becomes a meteor, or shooting star.

How big are they? Most meteors are no larger than the toenail of your little toe. Many are just the size of a grain of sand. (Really!) But some can be the size of your fist and, in rare cases, the size of a large dog or even a car. Most burn out before reaching the ground, but when a large meteor enters the Earth's atmosphere, it can survive it's fall and land somewhere on the planet.

Many meteors disappear into the water, never to be seen again. But some are found on land - especially on the Antarctic ice fields. (If a rock is found on an ice field, it can only be from a meteor, since there are no other rocks around.)

When a meteor lands on the solid surface of the Earth, it becomes a meteorite. They're hard to find because, to the untrained eye, they look just like any other rocks. Good luck. ★

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☆✮ Thank you for reading!! ★ ✯