THE USM SOUTHWORTH PLANETARIUM
207-780-4249     www.usm.maine.edu/planet
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70 Falmouth Street     Portland, Maine  04103
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43.6667° N                   70.2667° W
Altitude:   10 feet below sea level
Founded January 1970
Julian date:  2458682.5
 "Thanks to its plasticity, the brain can be thought
of as a tree of knowledge. When in full bloom, a tree blossoms: roots
give off branches, twigs, and leaves. Similarly, learning increases
interaction within the brain with more and more other neurons
establishing fuller and richer circuits. But if learning stops, the
brain, like a tree losing the luxuriant structure seen at full bloom,
reverts to a state corresponding to that of a tree in winter."
-RIchard Restak, MD
author of "Think Smart: a Neuroscientist's Prescription for Improving
Brain Performance."



THE DAILY ASTRONOMER
July 17, 2019
Arecibo Calling

Humanity's first deliberate interstellar call into the wild black
yonder is currently forty light years away and, during the time you
spent reading this sentence, will have moved another 1.6 million miles
closer to its destination, the Hercules Globular Cluster.* Though
considerable, the distance already traversed represents merely 0.16% of
its 25,000 light year journey. Many millennia will elapse until the
highly attenuated message finally infiltrates that vast globe of stars
and, perhaps, is captured and deciphered by any beings residing around
one of them. Assuming the message elicits a response and the recipients
know where to direct it, the reply will propagate through space for an
additional 25,000 years until reaching our remote descendants, who won't
have foggiest notion about the original transmission, thereby rendering
the entire experiment a pointless disaster.

That last paragraph covered the marketing angle. Now, we proceed with
the science.

In November 1974, astronomers using the Arecibo Radio Telescope in
Puerto Rico transmitted a three minute message at a frequency 2,380 MHz
toward M13, a globular star cluster in the constellation Hercules. This
message consisted of 1,679 binary digits now travels at light speed
toward this spherical distribution of more than 300,000 stars currently
located 25,000 light years from Earth.

Two highly notable Cornell astronomers, Frank Drake and Carl Sagan
devised this special message They chose 1,679 binary digits because
1,679 is a semi-prime number, evenly divisible by two prime numbers;- in
this instance, 23 and 73. Therefore, the sequence can only be arranged
in a 23 x 73 rectangle: 23 columns and 73 rows.** When so configured,
the sequence would appear as a grid work of ones and zeroes, each one
enclosed in a square. By darkening the zero squares and leaving the one
squares blank, one would produce the following image:

[image: Arecibo-message copy.png]

The message designers crammed as much information into this sequence as
possible: information pertaining specifically to Earth, the humans
living on it, and the chemical constituents comprising their genetic
material. The upper row consists of the first ten binary digits: the
key, as it were, for the symbols located at lower strata. Beneath the
numbers one finds binary representations of hydrogen, carbon, nitrogen,
oxygen and phosphorus: the principal elements necessary for Earth life.
Each of these elements contains a specific number of protons. (hydrogen
- 1; carbon - 6; nitrogen -7; oxygen - 8 and phosphorus -15). As these
elements will have exactly the same proton numbers -more correctly
called 'atomic numbers'- elsewhere in the Universe, any alien whose
scientific knowledge is at least comparable to our own will identify
these elements by number. Below these elements are listed the
nucleotides, organic*** molecules comprising the DNA double-helix that,
itself, is featured lower down.

Beneath the double helix stands a human. Here one encounters perhaps
the most complex message of the entire array. The human figure is next
to the binary number for 14 which, when multiplied by the wavelength of
the radio transmission (126 mm) yields 1.764 meters, the average human
height. (Good luck, aliens.) To the right is the binary representation
of Earth's 1974 human population of 4.3 billion.

Continuing down the sequence we encounter the solar system's retinue of
nine planets all aligned on one side of the Sun. The third planet is
displaced, indicating its special role as our home. (Note: the
International Astronomical Union's ill-advised Pluto demotion occurred
in August 2006, more than thirty years after transmission.)

Finally, at bottom, the Arecibo Radio Telescope itself: the 1,000 foot
wide radio dish that emitted the message presently progagating through
interstellar space.

Provided the message is received by some beings in the Hercules Cluster
(see the last paragraph for a spoiler), and that message is captured and
deciphered, perhaps we'll evoke a response from fellow sentient
creatures lurking somewhere in deep space. Though this notion might seem
far fetched, realize that, from almost all other perspectives in the
cosmos, Earth, itself, is lost in deepest space.

The problem, of course, is that this whole affair was essentially a
ploy: an excuse to demonstrate the radio telescope's formidable
transmission capabilities. The inverse square law tells us that when the
message reaches the 25,000 light year point, it will be so attenuated as
to be practically undetectable. Moreover -and this was the little detail
the Cornell astronomers opted to ignore- by the time the message does
arrive, the galactic rotation will have shifted the Hercules Globular
Cluster away from its present location. For all the trouble the
astronomers took to craft and transmit this message, they knew then as
we know now that the message will miss its target! Perhaps it is just as
well. Who knows what kind of message we might have received in return.



*This measured time assumes that, like me, you have an average reading
speed and aren't one of these insane speed reader types who go through
words like fugitives drive borrowed cars.

**Arrange the sequence with 73 columns and 23 rows and you'll have a
confounded mess that, knowing Earth's luck, would appear as a precisely
phrased invasion-precipitating insult in the alien's native language.

***carbon-based