Exoplanets Are Planets Too!

My first reaction was, “Oh no, not again!” I always maintained Pluto was a “planet,” no matter how the IAU redefined it in 2006. Are we going to revive that old trope again?

In the August 2013 Sky and Telescope, in an article of the same name, veteran writer David Grinspoon does just that, but with a new twist. “Recent discoveries have exposed the absurdity of the IAU’s planet definition.”

Well, of course! How did we miss the obvious? With recent discoveries of huge numbers of planets orbiting other suns, we are calling them “planets.” We can’t call them “dwarf planets” because those will be too small for current detection methods for quite some time to come.

But according to the IAU definition, the very first requirement of a celestial body be that it “(a) is in orbit around the sun.”

What the hell were they thinking?

An engineer, a physicist, and a mathematician are shown a pasture with a herd of sheep, and told to put them inside the smallest possible amount of fence. The engineer is first. He herds the sheep into a circle and then puts the fence around them, declaring, “A circle will use the least fence for a given area, so this is the best solution.” The physicist is next. She creates a circular fence of infinite radius around the sheep, and then draws the fence tight around the herd, declaring, “This will give the smallest circular fence around the herd.” The mathematician is last. After giving the problem a little thought, he puts a small fence around himself and then declares, “I define myself to be on the outside!”

Even this WordPress blog post is a wolf in sheep’s clothing, if you’ll pardon the terrible metaphor. Defining something so that it meets a predetermined selection criteria you need it to match is an ancient malady, and it’s not confined to religion and politics.

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Hubble Directly Images Black Hole Accretion Disk

For the full story see the NASA Hubble site: NASA/ESA managed to combine the powerful Hubble Space Telescope with the incredible sling-shot magnification of gravitational lensing to produce what appears to be mankind’s first visible-light image of an accretion disk. .

 

[quote]An international team of astronomers has used a new technique to study the bright disc of matter surrounding a faraway black hole. Using the NASA/ESA Hubble Space Telescope, combined with the gravitational lensing effect of stars in a distant galaxy [1], the team measured the disc’s size and studied the colours (and hence the temperatures) of different parts of the disc. These observations show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon.[/quote]

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Is Reality Digital or Analog?

I stumbled across this question in a Scientific American RSS feed. Does it really ask what it seems to? Unfortunately, that seems to be the case. This is what happens when you let a bunch of physicists loose in a sandbox and ask them to define it.

I have to be careful in framing my criticism of the real question posed here, since I lack any credible qualifications for judging questions of quantum mechanics. What I submit instead is that the “definition” of reality does not fall within the jurisdiction of the laws of quantum mechanics (whatever those turn out to be), any more than the glorious majesty of Half Dome or the Grand Canyon falls within the jurisdiction of the traffic court division of the Superior Court of California, County of Kern.

To my thinking, the question as framed is meaningless. Is the Empire State Building incandescent or fluorescent? How many angels can sit on the head of a pin? Continue reading

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Mars Hoax 2010

HOAX: Two moons 27th August 2010

The annual “Two Moons on Aug 27th” Mars e-mail is circulating again. Alas, the myth is another internet hoax, a best fit for the “liar liar pants on fire” category. Amateur astronomers already know this. This year, for the benefit of everybody else, we do our best to explain why.

A picture is worth a thousand words. See: http://www.astronomy.org.gg/hoax.htm

from astronomy.org.gg - click graphic for source article and image

The photo above is also true to my own experience, as I’ll narrate below.

Wikipedia on the “Mars Hoax” (emphasis mine):

Although nearly all of the claims made in the e-mail are true, the hoax stemmed from a misinterpretation of the third sentence of the second paragraph which states that “At a modest 75-power magnification Mars will look as large as the full moon to the naked eye”. The message was often quoted with a line break in the middle of this sentence, leading some readers to mistakenly believe that Mars would “look as large as a full moon to the naked eye” when, in reality, this only applies when a telescope with a 75-power magnification is used. This is the most likely source of misinterpretation.

We will never, EVER see a sight even remotely like the faked “two moons” e-mail image from Earth (or from anywhere else in the solar system). And 2010 is not even a particularly good year for telescopic viewing of Mars.

We already had Mars’ 2010 “closest approach” in January . Most non-astronomer citizens never would have noticed it. Phoenix and Bay area residents would probably be unable to see it with the naked eye unless it was an exceptionally clear night.

We actually have mathematical “closest approaches” every other year or so (Mars takes 687 Earth “days” to orbit the sun). Obviously, since both planets orbit the sun, there is always going to be some “closest” distance as the Earth swings round past Mars. That distance is not the same each year because the orbits if the two planets are not quite concentric, but elliptical — not quite perfect circles. Mars’ orbit is quite eccentric for a planet – about 9% longer on the long axis compared to the short dimension.

In 2003, we had the celebrated closest Mars approach “in 60,000 years”. Astronomers would have noticed Mars having an apparent diameter of almost twice its “farthest distance”. This difference doesn’t become readily apparent without a telescope of at least 6″ diameter.

The angular size of the Moon is about 1/2 degree (30 ARC MINUTES). By coincidence our Sun is of the same apparent diameter, which is why we can have perfect lunar eclipses. NASA confirms the angular size of Mars varies from a minimum of 3.4 ARC SECONDS to a maximum of 25.1 ARC SECONDS.

An arc second is 1/60 of an arc minute. Mars never stood a chance of looking close in size to the Moon!

From University of Wisconsin:

Even at its closest approaches Mars seldom appears larger than 26 arc seconds, or about 1/69 the apparent size of the moon.

Some sources compare this to the apparent size of a penny at 500 feet.

We all know from experience the Moon NEVER looks about the size of a penny at 500 feet. The Moon might look more like the size of a basketball at 100 feet. So how could Mars ever look like it was almost the same size? It can’t.

If that isn’t bad enough for backyard astronomers, more math (groan) conspires against us too. Remember that the area of a circle is proportional to the square of the radius. So, a planet of radius 1/2 will only display 1/4 the surface detail of a planet of radius 1, all other things being equal. A planet of radius 1/60 can, at best, display 1/3600 the surface detail of the larger one — not counting the distorting effects of the Earth’s atmosphere!

The 2003 Mars approach was a HUGE disappointment to Bob and me, and we (I) wasted a good deal of money trying to be ready to photograph this highly publicized event.

As actually viewed with the naked eye in 2003, it was hard to tell whether any kind of “disk” of Mars could be made out at all, or if Mars was just a really bright reddish point-source star like Aldebaran. With eye to our telescope eyepiece, we were barely able to see Mars’ polar icecap, but that was all. Bob and I tried to photograph Mars through the 8″ telescope with an expensive SLR camera body, without much success as we were inexperienced in photographing the night sky. Bob did the best job, holding up a “Brownie point and shoot” to the telescope eyepiece.

Our photo looked about like a penny at 500 feet. Copper-red, no surface detail visible at all. Unless you blow up the image (below), Mars looks like a little red dot in a huge black frame. This photo has been published here before. For a better color photo (looks like black-and-white), see also our Mars Elusive post (9-17-2003).

Mars 2003 - photo by Bob Sibley

The next “good” year for viewing Mars will be 2014, and it won’t get as good as 2003 again during our lifetimes.

Alex

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The Great 2012 Scare – Sky & Telescope

When we wrote our two October postings on the “2012” doom-and-gloomers, we debunked the myth, as many others have done. We also referenced the Sky & Telescope magazine’s impressive articles stating that the world is not going to end in any of the ways the movie or the Nostradamus and Mayan Calendar fetishists are predicting, at least, certainly not as the result of any known astronomical phenomenon expected in that year or century.

And we noted with regret that the S&T magazine’s website was “under construction” and we could not provide the customary link to document our sources.

The S&T editors have rectified that with a new November 11 online article and a couple of PDF downloads, free reprints from their magazine articles. They say:

If your friends and family are worried about the impending disaster — supposedly based on an ancient Mayan prophecy — we have the stuff you need to tell them …

November 11, 2009 | The world won’t end on December 21, 2012, no matter what ancient Mayan prophecies might imply. Noted archaeoastronomer E. C. Krupp explains the cause of this mania in November’s Sky & Telescope. But this issue is no longer available on newsstands, so we’re making Krupp’s article available as a free download.

The link to the article is here: The Great 2012 Scare

You should be able to download the PDF’s for yourself. Should you find the link broken at some future point, just reply to this posting, let me know. I downloaded them for myself and any friends who might want them by e-mail (they’re in my ‘Articles’ folder, Alex). I’ll post the PDF’s myself.

Cheers!

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Mystery Object Tears Star Apart?

Excerpted from the Sky&Telescope posting June 7, 2009, below.  We know that binary star groups sometimes consume one partner with cataclysmic results, so this article should be no surprise. Still, the idea of invisible black holes that can tear a star apart in 200 days is something that boggles the mind:

Update on Hubble Mystery Object

June 7, 2009
by Rachel Courtland, NewScientist.com

Remember the Hubble Mystery Object? In 2006 it steadily brightened, then steadily faded over the course of 200 days total, in a way that resembled no known type of variable object. Even its spectrum was inscrutable, leaving no sign of whether it was a flare on a very faint star in our own Milky Way or some enormous eruption billions of light-years distant.

What was it?
Now you don’t see it, now you do. Something truly in the middle of nowhere — apparently not even in a galaxy — brightened by at least 120 times during more than three months and then faded away.
K. Barbary and others

Now there’s a sign that it was the latter. And one new theory suggests that an odd, wandering, intergalactic black hole tore apart a star of unusual composition … Gaensicke and colleagues propose two scenarios that might explain the object. In one, a carbon-rich star swung too close to an intermediate-mass or heavyweight black hole, which pulled it apart. Some of the material made its way into the black hole, and some was blasted off in a flare that was seen from Earth as SCP 06F6.

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Fat Singularities and Skinny Infinities

Foggy Mist

HubbleIMAGINE that it is a really cold morning, and you have taken a REALLY hot shower. Not just the bathroom mirrors are fogged. The bathroom itself is filled with steam. In fact, the living room windows are even fogged over. So we open the sliding glass door for a little while to vent the moisture.

Instantly, or PDQ as near as anyone can tell, the mist expands out of the apartment to uniformly fill your entire hometown.
Continue reading

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Astronomy Magazine Sept 2007

Astronomy cover Sept 2007I must say it was a pleasure to open the latest issue of Astronomy magazine to find the 2008 Telescope Buyer’s Guide, a 20-page pullout written by Tom Trusock. Tom is a tribal elder at CloudyNights.com, and, as far as anyone knows, a Founding Father. He is also a prolific reviewer, an excellent writer, and the pullout is a keeper – informative, well-written and it sports an excellent layout.
Continue reading

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