Archive for the ‘astronomy’ category

Randall Munroe Is On The Case

November 12, 2014

Just to add to the deliciousness of the day, xkcd is more or less live-cartooning the Rosetta landing on Comet 67P/Churyumov-Gerasimenko.* (h/t @edyong209)

Nothing in my day promises to be as challenging/exciting as what that craft (and its controllers) are doing.  You?

Robert_Salmon_-_South_Sea_Whale_Fishing_II

*That link is a little wonky.  If the cartoon (number 1446) doesn’t come up, click on the random button at the top, and then click again on the xkcd logo.  Sorry.)

Image:  Robert Salmon (how cool is it that a whale-fishery artist goes by the name Salmon?), South Sea Whale Fishing II, 1831.  Connection to this post made obvious at the xkcd link, btw.

 

I Like To Think Of This As The Universe Expressing An Opinion About Today’s Incarnation Of The Party Of Lincoln

October 2, 2014

I mean, this picture sure seems to make a cosmic viewpoint clear:

Keyhole_Nebula_-_Hubble_1999 crop

Ah well.  It’s back to work for your humble bloghost.

Image:  NASA, The Hubble Heritage Team (AURA/STScI) – Space Telescope Science Institute, Keyhole Nebula, crop of the feature known as “God’s Birdie,” 1999.

The Most Exciting Sentence I’ve Read This Decade…

March 18, 2014

…Would be this one:

 We find an excess of B -mode power over the base lensed- CDM expectation in the range 30 < ` <  150, inconsistent with the null hypothesis at a significance of >  5 δ.

That’s from the abstract to this paper, released yesterday, in which the team using the BICEP microwave detector at the South Pole reports on their analysis of three years of data taken from 2010-2012.

So what’s that all about?  It’s the best evidence yet that a fundamental pillar of Big Bang cosmology is right, that a concept named inflation does in fact describe what happened within the first instant of the formation of our universe.  Here’s how Alan Guth, the inventor of the idea describes it:

This theory is a new twist on big bang theory, proposing a novel picture of ho the universe behaved for the first minuscule fraction of a second of its existence.

The central feature of the theory is a brief period of extraordinary rapid expansion, of inflation,  which lasted for a time interval perhaps as short as 10^-30 seconds.  During this period the universe expanded by at least a factor of 10^25, and perhaps a great deal more. [Alan Guth, The Inflationary Universe, p. 14.]

Guth’s initial version of inflation theory has been refined significantly since its origins in the late 1970s, and in its modern form inflation has become part of the basic toolkit of cosmological investigation.  The universe we observe doesn’t make sense unless something occurred to explain, for just one example, the way the universe looks basically the same everywhere, when viewed on the largest scale.  Inflation as the idea has evolved has become the best available explanation (though there have been competing models) for this and other observed cosmological properties.  But the challenge has been to find some tell-tale sign that shows* that inflation actually happened.

It’s been clear for a long time where such signs might lie:  in the cosmic microwave background (CMB),  a snapshot of the cosmos taken at a moment called “recombination,” when the universe cooled down enough to permit electrons and protons to come together to form (mostly) neutral hydrogen atoms.  Photons — light — that up till that moment had been embraced in electromagnetic dances with charged particles were then unshackled to fly freely through space, carrying with them the traces of where they’d been just before that liberation — which came just 380,000 years after the big bang.

J.M.W._Turner_-_The_Beacon_Light

Over time (13.8 billionyears), thatextremely hot (energetic) spray of light has cooled to 2.7 Kelvins — 2.7 degrees above absolute zero — and is now detectable as those very long wavelengths of light called microwaves.  This  microwave background was identified in 1965 as a generalized blur covering the entire sky; increasingly sophisticated measurements have revealed more and more detail.  Over the last twenty fiveyears those observations have turned into a probe of what happened between the big bang and the flash of the CMB itself:  each newly precise measurement constrains the possible physics that gave rise to the details thus revealed.  Step by step, each new level of detail narrow the options for what could have occurred during the big bang era — and the chain of events that lead from cosmic origins to us becomes increasingly clear.

In the 1990s,  improving resolution of CMB images revealed spots on the sky where there is slightly more energy in that microwave background — corresponding to regions in the early universe with slightly more matter-energy than surrounding regions.  Such variations account for why there are lots of galaxies full of stars in some places, and vast voids in other:  over millions and billions of years, gravity can work on very slight variations in initial density to sort matter into that kind of pattern.

With the advance of both space and ground based microwave imagers, it’s become possible to sample the CMB in vastly greater detail, and thus uncover much more than the simple (easy for me to say) evolution of structure in the universe.  For example, CMB researchers have identified several acoustic peaks in the background — literally, the ringing of the early universe, pressure waves produced by the interaction of light and matter in the very early universe.  The particular properties of those peaks reveal basic facts about the universe — and help distinguish between different theories about how we get the cosmos we inhabit from the big bang whose traces we see in the CMB.

Before today, the state of play was that CMB results were most consistent with the  predictions of inflation, compared with other candidate ideas.  At the same time though, observations that are consistent-with are not the same as direct observations of the cosmological equivalent of the miscreant’s fingerprints on the knife.  That’s what the BICEP results deliver.

In simplest terms:  modern theories of cosmic inflation say that immediately after some tiny perturbation occurs that marks the birth of a universe, it gets pulled apart by inflation — which you can think of as negative gravity, a gravitational field that stretches space-time.  The inflationary episode is so powerful that it expands the infant universe by orders of magnitude in fractions of a second — as some say, inflation provides the bang in the big bang — and it’s so violent that as space-time undergoes such wild tugs, ripples form.  Those ripples are gravitational waves — predicted by Albert Einstein, inferred from the behavior of pulsars, but never detected directly.  An observation of such primordial fluctuations, variations in the strength of the gravitational field from point to point in the early universe, would offer the first direct glimpse of traces of an inflationary episode marking the birth of our cosmos.

And that’s what BICEPs results contain:  the team led by John Kovac at the Harvard – Smithsonian Center for Astrophysics, Clem Pryke at the University of Minnesota, Jamie Bock at Caltech/JPL, and Chao-Lin Kuo of Stanford and SLAC report the detection of the signature of gravity waves in the CMB with the properties corresponding to those predicted to be produced by inflation.

In slightly more detail, the BICEP experiment observed a particular pattern of polarization in the light (microwaves) of the CMB that inflation would be expected to produce.   (Many more details:   web resources from the BICEP team and partner institutions;  quick semi-technical gloss on the results from Sean B. Carroll;  Matt Strassler’s take; Dennis Overbye’s account in the NYT.)

One key caveat before the wind up:  this is one result from one group.  It is reported with great confidence (that five sigma claim).  But something this big needs independent confirmation — data from the Planck satellite for example, or more ground based observations from other microwave detectors.  This isn’t yet a done deal.

Such confirmation (or disproof) will come fairly quickly — a few years at most.

In the meantime, assuming the data do hold up, what would that mean (forgive me) more cosmically?

At the very least:  that we now understand in previously unattainable detail how our current habitat emerged from nothing (or better, “nothing”).  That the idea of a multiverse — other patches of space time that underwent an inflationary episode to form island universes of their own — has now gained a boost (if one patch of space-time can inflate, so could others)….

…or to put in mythic terms:  there is grandeur in this view of life (the cosmos).  Paraphrasing an old friend, astronomer Sandra Faber, with this new, richer, more fully realized picture of the birth of the universe we have once again enriched that creation story that only science tells, the one that connects the earth we inhabit today with a process of cosmic evolution that we now can trace back all the way to just the barest instant this side of the point of origin.

A good day.

*To a close approximation — this is physics.  You want certainty, become a mathematician.

[Thanks to Dr Katherine J. Mack of the University of Melbourne, aka @AstroKatie, who helped make sure no egregious errors slipped through.  Any mistakes, major or minor, that remain are mine, all mine.]

Image:  J. W. M. Turner, The Beacon Lightc. 1840

PS:  Bonus video showing one of the founding architects of inflation theory receiving news of the result:

A Bit of Multi-Spectral Awesomeness For Your Delectation

July 9, 2013

This image has been around for a bit, but I just stumbled on it — so here you go:

719590main_Grid-Sun-orig_full

Per the NASA write up, this is a collage of images from the Solar Dynamics Observatory, mostly showing measurements of light at particular wavelenths, w. a bit of other information as well.

I want my own quilt  made to that design.

As the linked material says, the point isn’t just pretty pictures.  It’s that the characteristics of the light (electromagnetic radiation) detected up and down the spectrum reveal very specific details of the processes the produced each particular emission.  See, e.g., the wonderful story of the element that was, then wasn’t, coronium.

One more thing:  this image, or rather the investment required to make all the images that go into this collage, is an example of the kind of nice thing it will be harder and harder to get the longer our current Republican party remains in existence.  Just sayin…

We Are Stardust

May 29, 2013

Via Phil Plait (aka the Bad Astronomer), this gorgeous view:

CentaurusA_LRGB_120hours_3215x2406-X3

This picture of the active galaxy Centaurus A was made by Rolf Olsen, an amateur astronomer in New Zealand.  I can’t do better than Plait does in explaining why this sight is not simply beautiful, but astonishing:

The detail is amazing, and you really seriously want to embiggen it; I had to shrink it a lot to fit it on the blog. Going over the details at Olsen’s site just amazed me more and more.

First and foremost: He took these images with a 25 cm (10”) telescope that he made himself. That’s incredible. A ‘scope that small is not one you’d think you could get this kind of image with, but persistence pays off. It took a total of 43 nights across February to May of 2013 to pull this picture off.

Centaurus A is  a very interesting object — the product of galaxies in collision, it has a massive black hole gobbling up stuff in its center.  As Plait notes (with awe!), Olsen with his very modest-sized home-made telescope was able to resolve the tell tale jets that the black hole produces (see Plait’s piece for the close – ups).  I’ve done a little bit of star gazing, and I worked with Tim Ferris on the development of his Seeing in the Dark film — a kind of love note to the amateur astronomer community, so I have some sense of the skill and sheer stamina of those folks who spend night after night staring up.  And even with that as context, I can say that what Olsen does here is truly impressive.

So enjoy. Stare at that image (do hit the link for the big version — and check out Olsen’s gallery).  Note that in the shock of collision you likely get ramped-up star formation.  In star formation, you get planets.  With enough heavy elements (i.e., enough generations of stars aborning and flaming out), you get the basic chemistry of life.  Not saying there’s anyone looking back…but (allowing for the time lag)  you never know.

Consider this a cosmic open thread.

Image: Rolf Olsen, 2013, used by permission.

Just Because I Can

January 2, 2013

I’m doing what I shouldn’t here:  troll baiting.  In the version of this post up on Balloon Juice, a relentless troll whinged about the use of false color in rendering astronomical images both interpretable and beautiful.  What follows is (a) stuff I wanted to get off my chest and (b) an excuse to post some cool astronomical images.  Enjoy:

I love astronomy.  I’ve made a couple of films about telescopes, observatories, and the exploration of deep space made possible by the extraordinary instrumentation created over the last couple of decades.  Observational astronomy has undergone a true revolution in my lifetime, and we know more about our universe by direct examination now than we did before, say 1950 by an almost incomprehensibly wide margin because of the two great changes rung in by that revolution.

One of those is astronomy’s gain from the tide that lifts all boats — the incredible rise in precision engineering and the science behind it that underpins  so much of modern life, from the digitization of experience to the transformation of medical diagnostics to the tying up of the globe into an unprecedentedly swift, safe and reliable transportation network and so on.

The other truly transformative move in 20th century astronomy was (at least largely) specific to the domain of sensing, remote and direct alike:  the realization that it is possible — and important — to look up with detectors that can capture signals from anywhere on the electromagnetic spectrum from gamma rays to radio waves — and not just in the realm of the visible that has defined astronomy from Og the caveman to Hubble (and a little beyond).

Nothing new in any of this potted history, but there’s a bit of method to my madness.  The exploration of wavelengths longer than what humans can see (infrared-radio) and shorter (ultraviolet-gamma) has led to utterly new views of the universe, and insight into a whole range of physical phenomena that observations within the range of human sight could never yield.  For a quick gestalt on that point, take a look at this:

mwmw_8x10

I’m not sure how easy it is to pick up the identifiers to the left of each image — but the image shows us what our galaxy looks like when examined at different points along the electromagnetic spectrum.  When we go out on a clear night (preferably at altitude, away from a city), we see something that looks like the third strip from the bottom.  Looking at that, we have essentially no idea of what’s going in the sky — all the signal to be seen everywhere else up and down the picture.

Crucially, there’s a ton of science in (or enabled by) these various views.  Emissions of light from some object are signals of some physical process happening to produce that electromagnetic emission.  If a star or a galactic center or whatever is pumping out a ton of gamma-rays, that tells us a lot about what’s happening to produce so much light at such high energies — and the same applies up and down the spectrum.

But there’s a problem, or rather a feature of the observations that lead us to the insights available only when we have a multi-spectral grasp of our surroundings.  We don’t see X-rays.  Nor radio waves, nor any light that doesn’t fall within what’s called, for obvious reasons, the optical or visual band of spectrum.  To render those images interpretable, to make them available for communication to each other, we need to perform an act of translation.  That’s what’s going on above, when you see images labelled “gamma ray” or “radio continuum” with your own eyes, dressed up in lively shades of red and yellow, purple and blue.

To some (and now I’m getting to it) such coloring is a lie, propaganda with which NASA and space scientists in general trick us into paying for the observatories in space and on earth that generate the data behind the fibs.  To sane people, it’s what you do to help you think about and understand what it is you’re looking at/for.  And if as a field there is a value placed on aesthetically rich translations of the invisible into the seen?  Well, it might be because so many astronomers were first moved to make the night sky their home by images like this:

saturn-voyager

Which is what Saturn looks like in the optical range, as observed by the Voyager II spacecraft.  (Personal note: I was hooked on stuff in the night sky from the time I saw Saturn through a large telescope at Oakland, California’s Chabot Observatory.  I was about 10.  The sight of the rings swinging into view as I sat at the eyepiece has never left me.  Public cultural goods are good.)  There’s not much science in that picture, except for the deep pleasure it offers, sufficient to move many more than one into a life’s work.

All of which is prelude to one last image.  A commenter troll in this thread spent inordinate amounts of time and blather complaining about the terrible trickery and deceit involved in Hubble Space Telescope imagery, because, after all, the only thing that comes back off that instrument are strings of 1s and 0s that reflect measurements in various bits of the optical and near infrared chunks of the spectra.  The colors are “false” — which is to say not what a naked eye would see, if it had the light gathering capacity of a 2.4 meter-mirror and the ability to stare, unblinking for the requisite amounts of time.  The naive American public must, it seems, be protected from twin illusions of knowledge and beauty, lest it thus be gulled into funding more such instruments.  Or something.

To which, at long last, I say simply, get a life.  Or perhaps more in keeping with the tone of this establishment: copulate yourself with vigor — and an oxidized agricultural implement.

To put that into visual terms, let me offer up for your viewing pleasure an utterly falsely rendered picture that is both sublime and filled with the raw material of insight:

A star between 100 and 150 more massive than the Sun, about 7,500 light years from Earth.

This is a picture of the giant star Eta Carinae, and it’s a photoshop:  the blue image is from the Hubble Space Telescope, and shows the relatively cool remnants of an eruption in 1840 that blew off about 10 solar masses, leaving between 100 and 150 times the mass of our sun behind.  The orange imagery is a false coloration (a lie!) of x-ray data gathered by another NASA orbiting observatory, the Chandra X-Ray telecsope.  That shows what happens when fast gouts of material from the explosion smash into surrounding gas and dust, collisions that heat that shroud to upwards of a million degrees, which is what produces the energetic x-ray emissions.  The shape of those observations marks the limit of the region in which this desperately unstable star is interacting with its environment.

Eta Carinae attracts a lot of attention because it is a prime candidate to go supernova — and if/when it does, we’ll have almost scarily front row seats for the show.  The composite image above isn’t “necessary” for the investigations of its properties.  But it does provide a synoptic view of what’s going on right now, and it sure is pretty.

Which is what we know on earth, and, if not all we need to know, than at least a fine goad to get after the rest.

Your Tax Dollars At Work

January 1, 2013

NASA’s Picture of the Day for January 1, 2013:

716720main_hubble_new_year_full_full

Here’s the image caption:

The Hubble Space Telescope captured a spectacular image of the bright star-forming ring that surrounds the heart of the barred spiral galaxy NGC 1097. In this image, the larger-scale structure of the galaxy is barely visible: its comparatively dim spiral arms, which surround its heart in a loose embrace, reach out beyond the edges of this frame.

This face-on galaxy, lying 45 million light-years away from Earth in the southern constellation of Fornax (The Furnace), is particularly attractive for astronomers. NGC 1097 is a Seyfert galaxy. Lurking at the very center of the galaxy, a supermassive black hole 100 million times the mass of our sun is gradually sucking in the matter around it. The area immediately around the black hole shines powerfully with radiation coming from the material falling in.

The distinctive ring around the black hole is bursting with new star formation due to an inflow of material toward the central bar of the galaxy. These star-forming regions are glowing brightly thanks to emission from clouds of ionized hydrogen. The ring is around 5000 light-years across, although the spiral arms of the galaxy extend tens of thousands of light-years beyond it.

Image Credit: NASA/ESA/Hubble

Just think:  if the Teahadists have their way, none of the engineering or aspiration that made the Hubble possible would see the light of day (or night) in the future.  Just sayin’.


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