Happy Belated Flag Day from the Night Sky

“If anyone, then, asks me the meaning of our flag, I say to him — it means just what Concord and Lexington meant; what Bunker Hill meant; which was, in short, the rising up of a valiant young people against an old tyranny to establish the most momentous doctrine that the world had ever known — the right of men to their own selves and to their liberties.” –Henry Ward Beecher

Yes, folks, on Monday it was Flag Day here in the United States. Like many flags, there’s no shortage of stars on this one.

But these stars are merely symbolic, and not actually representative of stars in the night sky.

But there are some flags that go the extra mile for astronomical accuracy and utility.

The state of Alaska, inspired by the Irish Starry Plough, chose the constellation of the Big Dipper along with Polaris — the North Star — for their flag.

The Big Dipper (known elsewhere as a plough, a chariot, a coffin, a bear, or a cart) is one of the most recognizable constellations for anyone in the Northern Hemisphere. This is both due to the brightness of its seven stars (visible even in large metropolitan cities), but also because of its usefulness.

The two stars at the edge of the “cup” of the dipper (as opposed to the handle) point towards the bright North Star, Polaris. Although the constellation isn’t as bright as the Big Dipper, Polaris forms the tip of the handle of the Little Dipper.

For the rest of your life, if you find yourself in the Northern Hemisphere on a clear night, following the Big Dipper to the North Star will be a surefire way for you to find north.

But what if you live in the Southern Hemisphere? Well, although it’s slightly more involved, there are a number of flags to help guide you. Here are some.

From left-to-right (and click for a larger view), the Cocos (Keeling) Islands, Christmas Island, Tierra Del Fuego in Argentina, and the Australian Socceroos all show the same set of five stars: the Southern Cross.

I’m just joking around, Australia. I know what the real Australian Flag looks like.

This cross-like (or kite-like) configuration of four stars actually appears in two different places, so you need to look for the dimmer fifth star — Epsilon Crucis — to distinguish the Southern Cross from the others, especially the tricky False Cross.

But if you correctly identify the Southern Cross, you are well on your way to finding south in the night sky.

Unlike in the Northern Hemisphere, there is no bright star marking the pole in the Southern Hemisphere. (I heard you, Sigma Octantis, and you’re too dim to count!) So you need to be a little clever to find south.

Next to the Southern Cross, on the opposite side from that fifth star (epsilon crucis), are two extremely bright stars (Alpha Centauri and Beta Centauri) known as “Pointers”. This pair of stars, along with the Southern Cross, are fairly easy to spot. Once you’ve got them, draw an imaginary line perpendicular to the pointers and another imaginary line along the long edge of the Southern Cross, like so.

Where these two imaginary lines meet is the location of the South Celestial Pole, and that’s how you find south!

Two different stories from two different hemispheres, as told through flags! And while that’s pretty neat, I can’t let this post end without showing off the flag of Brazil. In my opinion, it’s the most astronomical of all the flags.

With 27 stars to represent their 26 states and 1 federal district, Brazil’s flag accurately depicts the locations and magnitudes of 27 major stars (most of which compose recognizable constellations) in the Southern Hemisphere. Unlike many other countries with stars representing states on their flag, each star represents a specific state or district. The flag depicts the sky over Rio de Janeiro on the morning of November 15, 1889, the day the Republic of Brazil was declared.

So happy belated Flag Day to all. Whether your home country/state/territory has stars or not on its flag, the astronomical skies are all yours!