Messier 13

Any alien lifeform that intercepts this message will immediately learn how easily we can be bullied and destroyed by a superior being, and they will also learn our home address.

Which kind of feels like a recipe for disaster, doesn't it? The message is headed for the Messier 13 star cluster some 25,000 light years away, but anyone could intercept this message while it's en route.

Since then, we've broadcast dozens of other messages too, emanating out from our tiny planet like proverbial lemmings leaping off a proverbial cliff.

In 2008, NASA even broadcast a Beatles song, apparently entitled Across the Universe Into Space.

They orbit high above and below the disk, some reaching distances of tens of thousands of light years from the galactic plane.

The cluster, known as Messier 13, one of the most famous globular clusters visible from the northern hemisphere, orbits through the halo at a distance of roughly 22,000 light years from the Sun.

These clusters are directly above and below the Sun in galactic terms, They are part of the vertical structure of the Milky Way, objects that exist in the directions the flat diagram never shows.

When you look straight up from the galactic disk, you are looking into a sparse swarm of ancient star clusters orbiting the galaxy in three dimensions, tracing paths that carry them high above the disk, and then plunging them back through it.

They orbit high above and below the disk, some reaching distances of tens of thousands of light years from the galactic plane.

The cluster, known as Messier 13, one of the most famous globular clusters visible from the northern hemisphere, orbits through the halo at a distance of roughly 22,000 light years from the Sun.

These clusters are directly above and below the Sun in galactic terms.

They are part of the vertical structure of the Milky Way, objects that exist in the directions the flat diagram never shows.

And now we can follow Mr. Shapley in a more detailed study of one of the globular star clusters also situated in the constellation of Hercules.

It is known by the name of Messier 13, which means that it is the 13th on the list of star clusters compiled by Messier.

It is an object of impressive beauty, a swarm of silent and crowded celestial bees, each one of which is a gigantic sun.

Many years ago I had occasion to photograph it with a long exposure by means of the wonderful 100 centimeter reflector of the Mudin Observatory.

The great 60-inch telescope of the American Observatory of Mount Wilson lends itself even better than that of Mudin to the examination of this ant heap of stars.

Thanks to its great focal length, which is 25 feet and can be lengthened to 80 feet, it easily separates the stellar images of the center of the mass.

On a photograph of Messier 13 taken with this unique telescope, we can already find, after only two minutes exposure, more than a thousand stars.

On prolonging the exposure to 11 hours, an image is obtained on which Professor Ritchie was able to count 30,000 stars brighter than the 21st magnitude.

These are dense, spherical collections of hundreds of thousands or even millions of stars.

M-13, also known as the Great Globular Cluster in Hercules Contains about three hundred thousand stars packed into a region about one hundred forty-five light-years across.

At the center of M13, stars are so densely packed that if you lived on a planet there, your night sky would be filled with thousands of stars as bright as Venus appears in our sky.

M13 is about twenty-two thousand two hundred light-years from Earth.

Four, why was it never repeated? Some say a genuine extraterrestrial signal would be repeated, but we haven't done that ourself.

For instance, in 1974, the, uh, Arecibo Observatory sent a single message toward the globular cluster M13.

It was never repeated.

If somebody in the other side had caught it, uh, they now have their own Wow! signal.