facts

Bat Facts

dr. dolittle — Thu, 29 Oct 2015 01:35:30 +0000

Bat Facts

With Halloween quickly approaching, I thought it would be fun to take some time to appreciate bats. Amazing animals!

dr. dolittle Wed, 10/28/2015 - 21:35

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Top 6 Facts about the year's final Solstice

esiegel — Wed, 18 Dec 2013 17:54:16 +0000

Top 6 Facts about the year's final Solstice

"In the depth of winter I finally learned that there was in me an invincible summer." -Albert Camus

As the year draws to a close, we approach a very special time of year, at least from an astronomical perspective. This Saturday, December 21st, will mark the Winter Solstice in the Northern Hemisphere (or the Summer Solstice in the Southern), or the date where the Earth's axis is tilted its maximal amount away from (or towards) the Sun, as viewed from an observer in the Northern (or Southern) Hemisphere.

Image credit: Mrs. Snyder at the Seven Hills School.

While it's pretty common knowledge that the Earth's revolution around the Sun in conjunction with its axial tilt is the reason for the seasons, the December solstice -- one of the two days where the Earth's tilt is maximally inclined with respect to the Sun -- brings a number of special things along with it. (Please note that all latitude-dependent ones apply equally to the Southern Hemisphere on the June solstice!)

Here are my top six.

Image credit: Earl Moser, via http://www.astro-tom.com/.

1.) A dedicated astrophotographer living North of the Arctic Circle could take the first-ever 360-degree star trail photo!

Never-yet-accomplished, Lewin's Challenge requires 24 hours of consecutive darkness, something that happens for six continuous months centered on the solstices at each of the poles. As we cycle through our orbit, the equinoxes mark a time when every location on Earth receives 12 hours of daylight and 12 hours of night. Subsequently, one of the poles plunges into darkness, with progressively lower and lower (numbered) latitudes surrounding that pole joining the party. This reaches its peak on the Solstice, where all latitudes within 23.5 degrees of the pole-in-darkness (so everyone north of 66.5 degrees on Saturday's Solstice) will receive 24 hours of continuous darkness.

If you can get there and leave your shutter open, properly centered on the North Pole, you could be the first one! Anyone in Utsjoki, Finland, want to give it a shot? And speaking of latitude...

Image credit: Ken Tape.

2.) Anyone living north of the 43rd parallel will, on the Winter Solstice, never have the Sun rise higher in the sky than it appears all day at the South Pole!

That's right, the South Pole -- one of our favorite metaphors for a cold, dark, remote place -- will have the Sun be higher above the horizon all day than locations like Madison, WI, Portland, OR, all of Germany, Poland, England and nearly all of Russia will see at any time during the day!

In fact, for a modest location like Portland, OR, with a latitude of 45.6 degrees N, it will take around a week for the Sun to reach an angle above the horizon that exceeds what you'd see at the South Pole, and for an observer at the Arctic Circle, that won't happen for another six weeks!

Image credit: Greg Benson at Wikimedia Commons.

3.) The Winter Solstice now occurs very close to perihelion, or the Earth's closest position to the Sun, but that is slowly changing over time!

The Earth's orbit around the Sun makes an almost perfect ellipse, making a complete revolution every year. Well, kind of. You see, there are two types of year: the tropical year, which we define as 365 (or sometimes 366) days, and is the amount of time it takes the Sun to return to the same position it was in the sky approximately one revolution ago, and the sidereal year, which is the amount of time it takes the Earth to return to the same location in space, relative to the Sun, that it was exactly one revolution ago.

These two measurements of years are slightly different from one another, by one part in about 26,000; combined with the smaller intrinsic precession of Earth's orbit with respect to the stars (mostly due to the other planets), we get that the Winter Solstice cycles through an entire orbit every 21,000 years. The Winter Solstice coincided with perihelion -- which now occurs just a couple of weeks later -- around 800 years ago, and has been progressively migrating away from it; in about 10,000 years, it will be coincident with aphelion, or the point of farthest distance from the Sun! Enjoy Saturday's Winter Solstice as the closest solstice to the Sun you'll ever experience for the rest of your life!

Image credit: NASA's Sci-jinks, via http://scijinks.jpl.nasa.gov/.

4.) The low position of the Sun in the sky means that the full Moon closest to the Solstice, at its highest, will be the highest full Moon above the horizon of the year!

Think about it; when the Earth's axis is maximally tilted towards the Sun and the Moon is full -- as in, on the other side of the Earth from the Sun -- that means the Earth's axis will be maximally tilted away from the Moon. (To within a maximum error of just 5 degrees, the amount that the Earth-Moon orbital plane is inclined to the Earth-Sun plane.) That means, in a broad sense, that just as the Sun appears to carve its lowest paths through the sky, the full Moons closest to your Winter Solstice carve their highest paths through the sky, and vice versa during the Summer Solstice!

So while Australians are enjoying the Sun riding its highest paths through the sky, here in the north we'll enjoy the nearly-full Moon doing the same thing!

Image credit: The Centre for Planetary Sciences at UCL/Birkbeck, using a pinhole camera.

5.) Solstice is Latin for "Sun stands still," and this is for a good reason!

For approximately a week in each direction around both solstices, the path of the Sun through the sky barely changes at all for all observers in both hemispheres. As such, our word for solstice marks exactly that occurrence, and explains why, if you track the Sun's path on a daily basis over the course of a year, you'll see nearly identical tracks near the bottom (marking the Winter Solstice) and the top (marking the Summer Solstice) of all such images.

And finally, as a historical fact, the Winter Solstice has an amazing significance for humanity as we long for the distant planets and stars.

Image credit: NASA's Apollo Image Gallery / NASA image S68-56050.

6.) It was on the Winter Solstice in 1968 that humans, for the first time, were launched to the Moon!

The Apollo 8 mission, the first manned mission to reach and orbit the Moon, was launched on the Winter Solstice in 1968, exactly 45 years ago this Saturday. The first humans to ever see the Earth from such a great distance, Frank Borman, Jim Lovell and Bill Anders began their journey away from Earth on the Winter Solstice, the darkest evening of the year.

Three days later, they plunged behind the Moon, and Earth became invisible for a few hours. When those few hours passed, this was what they saw.

Image credit: NASA / Bill Anders / Apollo 8.

As Bill Anders said almost immediately,

"We came all this way to explore the Moon, and the most important thing is that we discovered the Earth."

So enjoy the solstice however you see fit, and as you do, remember -- whether you're bathed in the longest day or the longest night of the year -- that there are some things that bring us all together.

esiegel Wed, 12/18/2013 - 12:54

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Umm.. I think aphelion is actually July 5th this year. Perihelion, or Earth's closest approach to the sun occurs January 2 at 4:48 UT.

LOL. You changed it already!

As your punishment for getting that wrong the first time, you must perform the calculus on the sun's angle for both winter solstice and summer solstice, taking into account the Sun-Earth distance to calculate the energy per square meter.

Never let me get away with proofreading my own post!

Actually the ecliptic plane is defined by Earth's revolution and "most" other planets are revolving around the sun in similar orientations. It is possible to measure and define the other planets "nodes" which are locations when the planets cross the ecliptic plane from south to north and north to south. These points are stationary in any local time frame but travel at a slow speed similar to the precession of the equinoxes around the plane. Thus in relation to the ecliptic, there are North or South latitudes for each planet and each planet's measure in right ascension is a merging of both latitude as here described and longitude pinpointed by projection to the ecliptic plane.

Actually right ascension is defined a bit more precisely and focusses on different aspects but the same point is defined both by the merging I describe here and the other system of measure that is right ascension.

slightly off topic but sun-related. (I've been away and am catching up on older posts. black holes, yay!)

I've read several times that the light made at the core of a sun like our own takes 50 million years to reach the surface. in essence, there's 50 million years of light "stored" in there. when a sun goes nova, I imagine those "trapped" photons get released at the rate of the explosive expansion of the core ... so in addition to the light "made" by the nova event itself, the catastrophe is accompanied by the 50 million years of light "stored up."

is this even remotely true?

~~~

more importantly, thank you so much for your "blog" (as a 60-year-old writer I really loathe that term). yours is not merely my favorite science blog, but my favorite blog. I don't understand why people think science is dry. you bring so much heart to it that you really make it poetry.

gratitude.

I am troubled by the fact that you have markes the first pic as "not to scale" ....thinking of the reasons that you had to do it just make me shiver....

@Ernest...its not really that long. I've seen figures ranging from 40,0000 to 1 million years. It depends on what assumptions you make for the density and opacity of the Sun at different layers.

KC,

I don't have a dog in this race (and no assumptions about density or opacity), I have just often wondered if this light is part of why a nova is so brilliant. the notion seems reasonable, but I've never seen it expressed explicitly. this is a lot of light, and I would think descriptions of nova would mention it.

http://www.sciencerecorder.com/gallery/index.php?pageNum_show_selected_…

@Ernest Johns #73 et al: The description you quote "light made at the core of the sun takes 50 million years [or 40,000, or 1 million, or whatever] to get out" is true-ish, but a dreadful oversimplification :-)

What happens, as a result of the density and opacity of the matter around the core, is that the light is repeatedly absorbed by some nucleus, then, after some time, new light is emitted by that nucleus.

Since the successive emission events are uncorrelated with the prior absorption, the new photons may be going in the same direction, the opposite direction, or crosswise.

If you tried, in some computer model, to launch a photon from the "exact center of the Sun", and followed all of the successive interactions, then you would discover that the last emitted photon that got up to the photosphere appeared some thousands or N-hundred thousands of years after the original launch.

Does that clarify things for you, or just make it more confusing?

@Ernest #7, KC #9: Ironically, Ethan quoted a value for the emission time in his latest post on variable stars!

"This would be extremely unlikely, as the time it takes a typical photon generated in the core to reach the stellar surface is on the order of 100,000 years, "

I didn't see that until after my previous comment. It doesn't change my description at all, but does serve to give you a benchmark for the timescale involved.

thanks all for your efforts.

oddly, I wasn't asking about the escape time of a photon from a sun's core. I was asking if this light contributes significantly to the brightness of a star going nova (I've never seen this expressed explicitly). I ignored the mechanism of photon transmission through a hot gas as ancillary to my question. my limited understanding is that photons are absorbed by atoms at discrete energy levels, pushing electrons into outer orbits, from which they will eventually return (at discrete energies which we observe as discrete color bands by which we can identify the specific atoms comprising that star.). this suggests a "storage" mechanism for a lot of photons. I'm much happier with a number like 100,000 years than 50 million -- but both numbers are hugely counter-intuitive. I would be happy with a number like "one year."

yet energy to be released as photons remains stored in those gazillions of atoms with electrons in higher orbits.

is this light released during a nova and does it contribute to the brilliance of a nova for the days it dominates the luminance of its home galaxy? my nephew wants to know.

qualifying our query even a little more.

we suspect the answer is "yes." but we know it's not a certain "yes." it's possible the sun blows itself apart and expands in such a way that jostling an atom just right so that it releases a photon is less likely rather than more likely, in which case that 100,000 years of stored energy remains stored in atoms exploding into space retaining high-energy-orbit electrons.

alternatively, the circumstances that encourage atoms to release photons might be enhanced and a lot of light released over a short period of time.

we don't have an informed opinion, or a dog in this race, just our layman's question.

Nice job on the post, BUT a few discrepancies. " the equinoxes mark a time when every location on Earth receives 12 hours of daylight and 12 hours of night." Not so. If the poles have either 12 hours of dark or sunlight and they are a location on earth then... Several others I noticed but I am not trying to correct you or make any negativity. You put alot into this and it is quite nice. I enjoyed it. Thanks.

@christopher There is one planet that has an east and west pole so the description of ascension would have to be different fromulaicly would'nt it? Since lat. is east west.

@Ernest (several): The photons in the Sun's "core" (really, all but the outer 5 or 10% thickness) aren't being "stored". They get emitted, absorbed, and re-emitted continuously, as part of the ongoing fusion process.

There isn't any "stored energy" there to contribute to a nova -- that process emits all of its energy in the form of a combination collapse (adiabatic heating) and runaway fusion.

Also, your correct description of _atoms_ absorbing and emitting discrete wavelengths (spectral lines) only applies to neutral or nearly neutral atoms. The Sun is a fully ionized plasma -- it consists of completely bare nuclei swimming around in a vast sea of free electrons. Under those conditions, photons don't travel very far before they interact with the electrons. That's why it's opaque.

Michael, thank you for your kind, awesome, and informative comments. you have two fans here. I really appreciate this strange new technology (internet and blogs) that enable a budding young aficionado of science to communicate with real working scientists and engineers.

again, thank you for your kind consideration.

/Ernest & Nephew

Weekend Diversion: True Facts About...

esiegel — Sat, 02 Feb 2013 12:39:51 +0000

Weekend Diversion: True Facts About...

"Get your facts first, then you can distort them as you please." -Mark Twain

I am unimpressed with speculations that have no basis in fact, but if you can show how your claims are factually grounded and arrived at, they're certainly worth a listen to. And if your facts, logic and extrapolations are sound, you might even, as Sarah Jarosz sings,

Tell Me True.

Of course, if they're a little suspect instead, you can either lead people astray, or alternatively, create some of the best humor and satire ever created.

This weekend, I proudly introduce to you a series of nature videos by YouTube user zefrank1: True Facts About (various animals).

Image credit: Helen Thomas of http://www.travelblog.org/.

There are many animals that most of us know so little about, including the baby Echidna, above. So when I found out that there was a video called True Facts About Baby Echidnas, I had to check it out. Little did I know, this would be one of the most amazing nature videos I've ever watched. (Caution, the videos below start with ads!)

And there I am, laughing at mother nature, and yet I've totally come away having mastered this fact:

The larvae of an echidna is sometimes confused for a gummi bear. A blood-flavored, crunchy gummi bear.

But this is just the start of what's fast becoming a series. There are other videos highlighting other animals that are equally, wonderfully informative. Like the angler fish.

If you got past the flounder/angler fish encounter, you managed to learn about one of my favorite varieties, the deep-sea angler fish.

The deep-sea angler fish collects glowy-glowy bacteria in its wavy thing to create a tiny little light. Because it's dark as hell down there, and someone needs to light up that pretty, pretty lady.

Then, to kick off the new year, was my favorite of all his videos so far, True Facts About Sloths.

Favorite moment?

On average, the sloth can move around three feet per minute, which is an impressive three feet per minute faster than a dead sloth.

And that was followed up by True Facts About The Seahorse.

The seahorse truly is remarkable for its mating and reproductive strategies, but I loved the True/False section at the end.

If you said "false" to any of those, you're a cynical bastard when it comes to love, because the seahorse does all three.

That's right it does! And finally, there are True Facts About The Tarsier.

Lots of good facts in here, of course, but my favorite moment has to be this:

Each one of its eyes is heavier than its brain, which might explain why it hasn't invented anything.

There's a brand new one up about the Leaf Katydid, but it's not quite as good as these five. Still, I'm optimistic that the "True Facts" series will continue to combine humor and science along with ridiculous pictures and videos of funny-looking and behaving creatures. What a fun find to enjoy this weekend, and I hope you enjoyed the budding series as much as I did!

esiegel Sat, 02/02/2013 - 07:39

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I can't believe I got into science and didn't know this great series of snark. Now its really, really worth it.

These were some of the funniest yet most informational videos i have ever seen. I could not stop laughing at all of them. I have never heard of the echidna or the tarsier or how strangely awesome they both are. I look forward to zefrank1's (http://www.youtube.com/user/zefrank1?feature=watch) videos in the future and to learn about other weird creatures.

Ze Frank is kind of a big deal on the internet:

http://www.ted.com/speakers/ze_frank.html

http://en.wikipedia.org/wiki/Ze_Frank

http://www.zefrank.com/

Oh my god, I can't stop laughing.

Facts about Atheists

grrlscientist — Sun, 27 Sep 2009 04:59:39 +0000

Facts about Atheists

tags: atheists, atheism, famous atheists, satire, zakiechan, streaming video

This video is NOT an argument for atheism... It's a defense of atheists from right-wing religious -- christian, muslim, jewish and other fundamentalist -- hate-mongers. This video received the award for "Excellence in Humanist Communications" from the Harvard University Humanist Chaplaincy.

grrlscientist Sun, 09/27/2009 - 00:59

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Interesting video. Nitpicking: Dennett is certainly a leading philosopher of the mind, and an avid student of evolution, but not an evolutionary biologist.

Bigger nitpick: according to Wiki, E.O. Wilson isn't an atheist either. I can't confirm the rumours that he worships the Ant God.

No one ever said you can't be intelligent or productive without a belief in God... the Bible's just saying that it's foolish to try to dismiss God and live your life without him, when it could be so much better.

I have many atheist friends who still strive to live a good and moral life. Just because you're an atheist doesn't mean you're depraved and morally bankrupt. You just have to wonder where those morals originate from.

Also... since your list is rather biased, here are a list of great thinkers who DO believe in God.
-Isaac Newton
-Martin Luther King Jr
-Abraham Lincoln
-George Washington
-John Adams
-Patrick Henry
-Copernicus
-Galileo
-Kepler
-Pascal
-Faraday
-Kelvin
-Samuel Morse
-Wilbur & Orville Wright
-CS Lewis
-TS Eliott
-JRR Tolkien
-Jimmy Carter
-Charlton Heston
-Sam Walton
-Dave Thomas
-Johnny Cash
-Elvis
-Andy Griffith
AND CHUCK NORRIS!

Totally beside the point; that was a very cool piece of music. I love that very electronic sounding down-tempo stuff.

Kaylin:

The problem is, MANY Christians feel that God is necessary to live a productive or moral life, and the quote from Psalms supports them: atheists are "fools" who are "corrupt" and whose deeds are "vile" and there is "no one who does good."

You may not understand just how deep this belief goes until you stand in our shoes. You've never had to "come out" as an atheist to believers in your family, and then have to explain to them that this doesn't mean you're going to go out raping and murdering people on the street for fun.

This video was not meant as an argument for atheism, it was meant as a defense of atheists against intolerance. If you feel that your atheist friends can still live a good and moral life, then you obviously aren't the target audience.

The target audience is the roughly 50% of Americans who would refuse to vote for a qualified atheist for President, or the 48% of Americans who would object to their child marrying an atheist.

Oh, and it also includes Chuck Norris, who is a prolific anti-atheist bigot. http://www.wnd.com/index.php?pageId=41572

Kaylin, actually I think I pretty much know "where those morals originate from".

In science, uncertainty is normal

bioephemera — Tue, 14 Apr 2009 08:05:45 +0000

In science, uncertainty is normal

As I put it at a blogging panel last fall, "in science, it is normative to be not sure." It wasn't my most eloquent moment, but at least AAAS' president-elect Alice Huang agrees with me that one of the biggest challenges to public science literacy is understanding the contingent nature of scientific "truth".

But probably the most difficult concept to get across to nonscientists is that we look at data and then use probabilities to judge those data. The public wants an absolute black-and-white answer. We may look at something that is 80 percent likely as being good enough to base decisions on.

We'd like absolute answers, but we realize that sometimes decisions must be made with partial data or some uncertainties. And ... as we collect more data, what we thought of as truth might change.

If we can be patient and explain this to nonscientists -- how we are seeking truth with the best tools available -- they are less likely to be negative or skeptical of our conclusions.(source)

Of course we need better science education to address this. But in the meantime, if I can make a request of my fellow scientists, especially those influencing policy, don't oversell your work. A public led to think there is certainty on a scientific issue when there isn't will feel betrayed when the scientific consensus evolves. And a public who doesn't grasp how dissent and uncertainty are part of the normal scientific dialogue is more likely to give credence to pseudoscientific views promulgated by outliers with no real credibility.

During the recent Origins Symposium at ASU, which aired on NPR's Science Friday two weeks ago, one of the panelists (I think it was Lawrence Krauss) said:

We tend to sometimes hype things too much, and we have to beware. We've got to be careful about saying what is likely to happen. We want to promote things - after all the Large Hadron Collider costs a lot of money, and we try to convince people to spend money to do something. And we often like to say it's going to recreate the early universe. . . and sometimes that comes back to bite us. . . I think it's very important that scientists try of course to get people interested in what we're doing, but not overhype the situation, because it's always bad. And in fact, it's exactly that. If we say we're guaranteed to discover all these new particles in the LHC, and we see nothing, how are we supposed to come back later and say, 'you know, that was what we really wanted.'

Exactly! Although another panelist (I think it was Brian Greene) then noted that sometimes overhyping things - for example, asking whether the LHC will create a black hole - sometimes opens up an opportunity to convey accurate information. But that's a risky strategy. Listen to the entire interesting discussion here.

A failure to understand the role of uncertainty and evidence in science may be why a lot of people espouse the views criticized in this video, popularized lately on Pharyngula:

I'd be showing that video in my philosophy of science course, if I were still teaching.

bioephemera Tue, 04/14/2009 - 04:05

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education

Science

Science in Culture & Policy

In my experience, the problem is usually the opposite --- a reflex refusal to draw a conclusion even from very good data. Instead, what should be conclusions are buried in a steaming heap of qualifiers, reservations, lists of what could be wrong, tabulations of uncertainties, and on and on.

What scientists need to do is to quantify uncertainty and draw conclusions anyway. This is critically important in policy-relevant areas where the over-emphasis on uncertainty has very bad real-world consequences.

All of the usual cautions aside, the public wants to know if something is a good bet. As in, "can I trust my child's health to this vaccine?" Absolute certainty comes across as not having respect for the parent's concern, qualifiers come across as lack of confidence.

"The simplest thing I can tell you is that I trust this information enough that I gave the vaccine to my children" is more along the right direction.

With all due respect, both of you are making my point for me. :)

The public is frustrated when scientists hedge their conclusions with "ifs" and "maybes" precisely because the public doesn't understand that science is about finding a preponderance of evidence, not about finding absolute truth. That's a science education/science literacy problem.

It may be tempting for scientists to respond to confusion and frustration by overstating the evidence and saying, "Fine: THIS is the truth." But ask yourself what the downside of that strategy is. Communication research shows that when a strong, forceful message is proven false, it isn't just ignored, it actually increases resistance to future messages. Basically, if scientists exaggerate their evidence to support a message, then when the public realizes several studies later that the message was premature or inaccurate, they will be more skeptical of science in general and trust scientific experts less.

That's not good for us, is it? Especially when scientists advise policymakers, who make policy based on their recommendations. That's why it's important to convey that research has caveats and that science doesn't give you absolute certainty. It's not easy, but it's quite possible to do that while making policy recommendations. I have colleagues who do it all the time.

Being able to explain research clearly to the general public, like in a newspaper interview, is a different issue. Of course the public doesn't need to hear a long list of caveats about why an experiment may or many not have proven something or other. That's common sense! Researchers who do that don't have a gift for communicating to the public. Good science communicators can convey both the scientific consensus on an issue, while also noting the limitations of a study that are relevant to the audience - for example, if a clinical trial was only done on men and not women, or had a very small sample size.

With all due respect, both of you are making my point for me. :)

Thank'ee kindly, Ma'am. We aim to please.

Honestly I thought that video was thoroughly contrived, but I wouldn't mind showing it to the execs at SciFi channel who keep renewing Ghosthunters!

COFFEE CAUSES CANCER ELEVENTY!!1111!!!

COFFEE PREVENTS HEART DISEASE INFINITYQ!!111!!!

COFFEE DOES NOTHING BAJILLIONN!!1111!!1!!

COFFEE CAUSES ICE CAPS TO MELT!!11!!!

The problem is not scientists. The problem is dumbfuck "science journalists" who copy paste press releases and then add a fuckton of intensifiers and dramatifiers.

ROTFLMAO! Science journalists who say those kinds of things are indeed a blight on the face of the Earth. We can all drink a Jameson to that!

This is why the best scientists make the worst expert witnesses. Lawyers and juries like witnesses who are sure of things rather than witnesses who will only say that "the evidence is consistent with" whatever theory he or she is there to support.

Damn the lower half of the bell curve . . . they're the only ones that can't find excuses to get out of jury duty!

Great point, Chris! I think being a neuroscientist, and thus knowing all about the faults in human memory, will probably get me off any juries for the foreseeable future.