What unit of measure was created specifically to describe the energy output of supernovas?

Image via WikipediaHere's a fun fact for you: I am approximately 56 attoParsecs tall. Contrary to what Han Solo would have you believe, a parsec is a unit of distance. One Parsec is roughly 3.26 light years, or 3.085 x 10¹⁶ meters. The prefix atto describes 10^-18 Parsecs. Carry the math and you get 3.085 x 10^-2 meters, or 3.085 centimeters. Thus, at 5'8" I am roughly 56 attoParsecs tall.

There are lots of oddball units of measure like the attoParsec that have fallen into regular scientific usage, though many of them have more than mere amusement behind their origins.

Take a barn, which is equal to 10 square femtometers (10^-28 m²). That's the cross-sectional area of a typical uranium nucleus, which is a scale of area that comes up a lot in nuclear magnetic resonance research. Describing the nuclear cross-section of uranium as "big as a barn" is ironic, but the unit has practical applications. Scientists don't enjoy using scientific notation much more than the next geek, so they create units of measure that let them use conventional numeric terms when describing observed experimental values.

Besides, it's much more fun to talk about barns than it is square femtometers.

Not all unconventional units of measure are there to accommodate extremely small scales. Quite the contrary. The Galactic Year (GY), for example, is roughly equal to 250 million years -- the length of time it takes for the Earth to complete one revolution around the Milky Way. Earth is roughly 20 GY old, and the Cretaceous-Tertiary Extinction Event that wiped out the dinosaurs occurred roughly 0.4 Galactic Years ago.

So what's the most out-of-scale unit of measure in use today? How about one that can describe the entire lifetime output of our sun without sneaking up on double digits. It's the same unit of measure explicitly designed to describe supernovas.

What unit of measure was created specifically to describe the energy output of supernovas?

What name for a 10th planet did authors Douglas Adams, Larry Niven, and Arthur C. Clarke coincidentally "agree" on?

Image via WikipediaI'm overloaded this week, despite it being the 31st anniversary of the publication of The Hitchhiker's Guide to the Galaxy. Thus, today's truly trivial is another recycled Geek Trivia with a Douglas Adams bent:

The "formal" search for a 10th planet (to abuse the term loosely) began in the early 1900s when none other than Percival Lowell — the astronomer who basically bankrolled the search for the eventual discovery of Pluto — predicted that another Jupiter-esque gas giant must reside at the edge of the solar system. ... It turns out Lowell and his contemporaries just didn't have good data on Uranus and Neptune. When Voyager 2 finally did flybys of these orbs in the late 1980s, suddenly all the mathematical basis for Lowell's "Planet X" disappeared. Nonetheless, the Planet X concept was now a part of public consciousness, and an untold number of writers set about to use the "10th planet" as a plot device in their stories. ...

Still, one name seems to appear more often than most when authors and screenwriters christen a fictional Planet X. Inspired by the traditions of naming local worlds after figures from Greco-Roman mythology, several notable science-fiction scribes — including Douglas Adams, Arthur C. Clarke, and Larry Niven — coincidentally managed to "agree" on this planetary moniker.

WHAT NAME FOR A 10TH PLANET DID AUTHORS DOUGLAS ADAMS, LARRY NIVEN, AND ARTHUR C. CLARKE COINCIDENTALLY "AGREE" ON?

Get the answer here.

Related articles

• Happy Douglas Adams Day! (en.akihabaranews.com)
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• Hawking, Sagan and Clarke on God, The Universe And Everything Else (singularityblog.singularitysymposium.com)

How many dwarf planets are bigger than Pluto?

Image via WikipediaFour years ago today, the International Astronomical Union voted to revise the current IAU definition of a planet -- adopting the one that didn't include Pluto. This, of course, led to some blowback in the astronomy community (and the sci-fi/internet community, too). Team Pluto, however, didn't have much in the way of empirical evidence to back the position Pluto deserved to stay -- especially since it wasn't even the largest member of the newly minted dwarf planet group to which it now belongs.

How many dwarf planets are bigger than Pluto?

Truly Trivial: How many extrasolar planets have official nicknames?

Image via Wikipedia

Today is a major anniversary in planet-hunting circles, as 14 years ago on this date scientists announced discovery of the first traditional planet orbiting a major star other than our own sun. That is to say, we found the first real alien planet.

On Oct. 6, 1995, scientists Michel Mayor and Didier Queloz announced they had observed a planet orbiting the star 51 Pegasi, which is just over 15 parsecs from Earth (that's about 50 light years or 1.28 Han Solo Kessel Runs) in the middle of the constellation Pegasus. The planet is now called 51 Pegasi b, with the lowercase letter indicating that it was the first object found in the 51 Pegasi system besides the star itself. Thus was born the formal exoplanet naming convention which, like so many scientific traditions, starts out logical but can get really confusing.

The trouble with the International Astronomical Union's exoplanet naming conventions is twofold: They weren't honored for the first exoplanets discovered, and they get pretty screwy when applied to multi-exoplanet star systems. As noted above, 51 Pegasi b was the first "traditional" planet found orbiting a major star. That is to say, it was the first planetary body found orbiting a star not unlike our own sun. 51 Pegasi b was not, however, the first planet found outside our own solar system.

Planets PSR B1257+12B and PSR B1257+12C were found orbiting the pulsar PSR B1257+12 in 1992, three years before 51 Pegasi b. Note the uppercase designations of the planets, rather than the lowercase tradition started with 51 Pegasi b. Since the pulsar planets were the first discovered and because they orbit a pulsar rather than a regular star, their naming convention was largely ignored when "real" planetary discovery started. The original designations of the first planets were grandfathered into official IAU catalogs rather than retroactively changing their names. (When a third, more closely orbiting planet was found around PSR B1257+12, they called it PSR B1257+12A, just to keep the confusion going.)

As noted, the accepted IAU convention is to label planets in order of discovery, rather than in order of orbital distance from the star. Thus, 55 Cancri e is the innermost known planet in the 55 Cancri system, but has the later letter designation because it was the fourth planet discovered around that star. As more massive planets are easier to find, and more massive planets tend to orbit farther from parent stars than do less massive planets, this erratic lettering system will likely become more common.

Planetary naming issues are also more complicated in multi-star systems, as stars are designated with uppercase letters, and those designations are combined with lowercase planet labels. Thus the second planet around the second star in the 16 Cygni system is 16 Cygni Bb.

No wonder 51 Pegasi b is referred by many scientists by its common name, Bellerophon, rather than by its formal IAU designation. We all grew up calling Spock's home planet Vulcan, rather than 40 Eridani Ac. It's a wonder more planets haven't been given common names.

In fact, how many extrasolar planets have been given official IAU-approved common names?