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The Tenth Planet Shrinks Under Hubble's Gaze
starexplorer2001 writes "An object called the 10th planet by some astronomers is not as large as previously thought. New images of 2003 UB313 (aka Xena) were delivered by the Hubble Telescope and showed up as only 1.5 pixels! Now, some are calling to demote Pluto and kill Xena."
Maybe it's all black except for a bright white spot.
New Face discovered on Mars
A pixel is small, but nowhere near subatomic. It's measured only in microns.
When photons are distributed over the CCD surfrace, it has some measureable shape (e.g., Gaussian) which can be fitted as such to characterize the shape. The quoted size of 1.5 pixel is, I think, the FWHM of the fitted Gaussian function that characterize its source.
Ah, I still remember fondly the first time I saw a slashdot thread climb to a few hundred posts of argument about 'what makes a planet a planet?'. If ever a term was crying out for a rigid, ostensive definition from astronomers, it's 'planet'. From the ancient greek word for "wanderer", if we don't tighten it up some, the argument will come trotting out every time someone finds a rock doing laps about the sun. Stays within 10 degrees of the ecliptic, say 3,000km across...that works for me.
A pixel is small, but nowhere near subatomic. It's measured only in microns
By atomic, the author means it cannot be divided further. This was the original meaning of atom. Atomic is a word used in computer science to indicate an operation that can't be interrupted. It either happens completely, or doesn't happen at all.
AccountKiller
As George Carlin said pollution; Earth will be fine. We might be fucked; but the earth will be A-OK.
It can be derived with trigonometry:
(angle)*distance_to_the_object == size_of_the_planet
which are
(1.5pixel*0.025"/pixel)/(60*60*57.3radian/") * 100AU * 1.5e8 km/AU ~ 2700km.
If you read the article, you'll find that the size is only 1400km, though.
The difference results from the fact that the measured size of 1.5 pixel
includes the size of its point spread function for the HST/ACS/HRC (i.e.,
even a true point source show some finite size in optics...something we
cannot beat).
Well, what kind of a name should that be anyway? Xena is not a roman god or goddess, not even a small one like Luna, Nike or Pluto.
So if this object should be called a planet, here's the proper list of names to choose from:
Acca Larentia, Alemonia, Anna Perenna, Carmenta, Carna, Consus, Dea Dia, Feronia, Flora, Fons, Furrina, Maia, Nike, Ops, Pales, Pomona, Portunus, Robigus, Silvanus, Veiovis, Vertumnus, Volturnus
everything else is not acceptable.
"The more prohibitions there are, The poorer the people will be" -- Lao Tse
Don't forget it's a reversed (negative) image, so Xena itself is dark and the background of space is white.
I think if you look very closely you can see a few faint stars in the background...
All the Pixels around it were black except for one that was white, and one next to it that was grey, 1/2 white, 1/2 black. The pixel averages everything in the space it covers. I don't know if they actually use black or white or not, but that's how it works. Does that simplify things?
Someone save me from this sanity.