Star Gazing 101

Identify prominent stars and constellations in the night sky

Anyone who has stepped outside after dark has undoubtedly stared at the myriad twinkling stars in the sky. Stars can help you find your way, predict the weather, and more. But which stars are you looking at?

Improve your night-sky knowledge using a technique called "star hopping." Robert Hale, senior educator at the McAuliffe-Shepard Discovery Center (a planetarium and space science center in Concord, New Hampshire), says to find the Big Dipper first. Then you can "hop" to other prominent constellations. It’s a lot more fun to do it this way than using your iPhone app — and works even when you have no cell signal!

Big Dipper: Formed by the seven brightest stars in the constellation Ursa Major (aka "Big Bear"), the Big Dipper is visible year-round in the lower 48 states. It circles around the North Star counter-clockwise. Consider the sky in the northern hemisphere as a clock face, with due north at the center. In June, the Big Dipper will be at the 10 o’clock spot with its ladle sideways. (Looking for the bear shape? The handle of the Big Dipper is the bear’s tail, and the ladle is the hindquarters.)

North Star: The two stars at the end of the Big Dipper’s ladle (called Merak and Dubhe) point straight to the North Star. The North Star is also named "Polaris" because it sits over the North Pole. It appears stationary in the night sky, making it useful for navigation on land and sea.

Little Dipper: The North Star is also at the end of the handle of the Little Dipper or Ursa Minor (aka "Little Bear"), which, like the Big Dipper, is made up of seven stars. "The Little Dipper is a good weather gauge," says Hale. "The two stars at the end of the cup and the North Star are always bright, but the other four are fainter. If it’s clear and cold, minus 10 degrees F in the winter, you can see them. If it’s hazy in the summer, forget it."

Cassiopeia: The constellation Cassiopeia lies almost directly across the North Star from the Big Dipper. Its five bright stars form the five points of an "M" or "W," with one side a little wider and shallower than the other. To find it, go from Merak and Dubhe to the North Star, then turn slightly southwest and keep going to the opposite side of the celestial "clock." Cassiopeia and the Big Dipper never set, so you can use them along with the North Star to find your way.

Andromeda: The only galaxy other than our own that’s visible with the naked eye, Andromeda looks like a faint smudge of light. The deeper point of Cassiopeia’s "W" aims at Andromeda. "Everything you see in the night sky is part of the Milky Way, except for Andromeda," explains Hale. "It’s 2.8 million light years away, which means the light from it you see tonight left Andromeda 2.8 million years ago."

Orion’s Belt: Three bright stars in a slanted row form Orion’s Belt — the easiest way to identify the constellation of Orion (the hunter). When viewed through binoculars, the stars on the belt are deep blue. Orion’s Belt is almost due-south in the night sky. To find it, simply turn your back on the North Star.

Cloud Clues

Read the sky to forecast a storm

It happens to the most experienced outdoors people. You head out on a bright, sunny day and suddenly find yourself in the path of thunderstorm. Avoiding such a potentially dangerous surprise may be as simple as looking up. Clouds hold important clues to the weather — if you know how to read them.

Forecasting the weather using clouds starts with recognizing how high the clouds are. "There are three categories of clouds — low, medium, and high," says Todd Chambers, a meteorologist with the National Weather Service. The height of the cloud’s base determines which category it falls into. Above the continental United States, "low clouds are at 6,000 to 8,000 feet. Medium clouds are at 8,000 to 15,000 feet. High clouds are above 15,000 feet — higher as you go north," Chambers explains.

The second step is to determine the type of cloud. According to Chambers, there are two basic low-level clouds: "stratus" and "cumulus." If the weatherman uses the prefix "alto" before these two cloud types — "altostratus" or "altocumulus" — he’s referring to medium-level clouds. Cirrus and cirrocumulus clouds are the main types of high-level clouds.

After you determine the level and type of cloud, its speed and direction — not only across the sky but also up or down — are important clues to approaching weather.

Stratus clouds form a white sheet across the sky. "If altostratus clouds trend lower, there will likely be some precipitation in a few hours," says Chambers. "It depends on the temperature, but [sinking] altostratus clouds generally mean unsettled weather in a gentler weather pattern without strong winds."

Cumulus clouds look like puffy pillows on fair days. Most cumulus clouds don’t bring precipitation. They are the result of the sun heating pockets of land. The air over these warm spots rises and cools, forming small, cotton-like clouds. However, when instability is intense and cumulus clouds accelerate in size and mass, they can form thunderheads.

According to Chambers, three conditions must be in place for thunderheads to form:

1. The air is lifting quickly.

2. Moisture is in the air.

3. The atmosphere is unstable — typically when the surface of the Earth is warm (such as 75 degrees F) and the air at 30,000 feet is cold (such as minus 20 degrees F).

If an anvil-shaped top forms on a tall cumulus cloud, a thunderstorm is about to hit and could be accompanied by hail or lightning.

Cirrus clouds are also caused by lifting air but on a broader scale. The jet stream pushes moisture around the globe from west to east. As that moisture rises and cools, thin, wispy cirrus clouds form. "In the saying, ‘Red sky in the morning, sailors take warning,’ the red is the reflection off cirrus clouds," explains Chambers. If you are in the eastern United States and see cirrus clouds to the west, a storm is coming.

But not necessarily in the Rocky Mountains. Big mountains also create a type of cirrus cloud called rotor clouds, which are not precursors of precipitation but might mean strong winds. Rotor clouds, which form near mountaintops, look stationary because the wind is moving like a breaking wave over the mountains. If a rotor cloud forms, Chambers advises hikers to get out of the area.