Astronomy
esiegel | March 30, 2016“When a star goes supernova, the explosion emits enough light to overshadow an entire solar system, even a galaxy. Such explosions can set off the creation of new stars. In its own way, it was not unlike being born.” -Todd Nelson
In 1604, Kepler's supernova went off, the last Milky Way supernova visible to naked-eye skywatchers here on Earth. Yet since the development of radio and X-ray astronomy, other, more recent supernova remnants in our galaxy have been found. They've only been invisible to the naked eye because of the galactic gas and dust that blocks their visible light. In 1984/5, the…
esiegel | March 28, 2016"Every single time you make a merger, somebody is losing his identity. And saying something different is just rubbish." -Carlos Ghosn
A galaxy cluster is the largest individual bound structure in the Universe, containing anywhere from dozens to thousands of times the mass of our Milky Way. Yet as the cosmic web grows and evolves, many such clusters merge together, creating the largest cosmic trainwrecks in the Universe.
Image credit: NASA / STScI, of cluster MACS J0717.5+3745 in the optical, courtesy of Hubble Frontier Fields.
While very little evidence of a catastrophe is visible in the…
esiegel | March 21, 2016"The night has a thousand eyes, and the day but one;
Yet the light of the bright world dies with the dying sun." -Francis William Bourdillon
When we look for the brightest, bluest, most massive individual stars, we're restricted to looking nearby, since it's impossible to resolve individual stars at distances that extend much beyond our own galaxy. So how surprising is it, then, when the most massive stars we've ever found aren't in our own galaxy, nor in any of the monster galaxies we've found nearby, but in a small, satellite dwarf of our own: the Large Magellanic Cloud?
A combination of…
esiegel | March 17, 2016“The truth is you can be orphaned again and again and again. The truth is, you will be. And the secret is, this will hurt less and less each time until you can't feel a thing. Trust me on this.” -Chuck Palahniuk
The planets we know of -- in our own Solar System and beyond -- all have something in common that we routinely take for granted: the fact that they all orbit stars. But not only isn't this necessarily true of all planets, it might not be true for most planets.
Image credit: NASA / JPL-Caltech.
When we run simulations of planetary formation around stars, we find that a great many…
esiegel | March 14, 2016"True realism consists in revealing the surprising things which habit keeps covered and prevents us from seeing." -Jean Cocteau
Each time you look at a photograph of the Universe, you aren't just seeing it as it was at a particular moment in time, but also in a particular wavelength (or set of wavelengths) of light! Different wavelengths can reveal different phenomena and components of the Universe, from dust and gas to starlight, plasma, black holes and beyond.
The view of the galactic center in four different wavelength bands. Atop, from the ATLASGAL survey at 870 microns; below that, from…
esiegel | March 7, 2016"This is in a real sense the capstone of the initial missions to explore the planets. Pluto, its moons and this part of the solar system are such mysteries that New Horizons will rewrite all of the textbooks." -Alan Stern
The New Horizons mission surprised everyone last July when it revealed Pluto to be a world that varied significantly in both terrain and color. Instead of a uniform, reddish-hued icy world, it was revealed to have mountains, craters, smooth plains, pitted regions and more, which range in color from white to yellow to deep red.
Image credit: NASA/JHUAPL/SwRI, of the…
esiegel | March 5, 2016
“Youth always tries to fill the void, an old man learns to live with it.” -Mark Z. Danielewski
There are plenty of scientific myths that go around, including many that were generated recently by so-called science communicators that actively harm public knowledge. One of them was a now-famous image of a dark nebula silhouetted against a star field, claiming that this was a hole in the Universe a billion light years across with no matter in it.
Image credit: ESO, of the same object in a composite of visible, near-IR and farther-IR light.
Not only is the image itself a completely…
esiegel | March 4, 2016“Whenever I gaze up at the moon, I feel like I’m on a time machine. I am back to that precious pinpoint of time, standing on the foreboding — yet beautiful — Sea of Tranquility. I could see our shining blue planet Earth poised in the darkness of space.” -Buzz Aldrin
Seen from afar, Earth is often described as a pale blue dot. But why is our planet blue? Is it because the skies are blue? That can't be right, or the clouds and icecaps would appear blue-hued as well. Is it because the blue skies are reflected by the oceans? That can't be right either, or we wouldn't see different shades of blue…
esiegel | March 3, 2016"Our spectroscopic observations reveal the galaxy to be even farther away than we had originally thought, right at the distance limit of what Hubble can observe." -Gabriel Bremmer
One of the holy grails of cosmology is to measure, directly, exactly when the first stars and galaxies formed in our Universe. The Hubble Space Telescope has been pushing the distance record farther and farther back, with its measurements typically confirmed by ground-based, spectroscopic follow-ups. This time, however, the new record-holder was so distant that confirmation needed to be done from space: by Hubble…
esiegel | March 2, 2016"From a little spark may burst a flame." -Dante Alighieri
Last week, it was reported that the mystery of fast radio bursts were solved, and that they were due to the merger of a neutron star with another collapsed object, well outside of our galaxy. However, not only was that analysis fundamentally flawed, but a new paper out today identifies fast radio bursts that repeat, a dealbreaker for the merger scenario.
Image credit: Alex Cherney, of the Australia Telescope Compact Array, where the follow-up observations were performed.
Instead, it's thought that these events come from the…
esiegel | February 29, 2016"Some of them burn slow and long, like red dwarfs. Others -- blue giants -- burn their due so fast they shine across great distances, and are easy to see. As they start to run out of fuel, they burn helium, grow even hotter, and explode in a supernova. Supernovas, they're brighter than the brightest galaxies. They die, but everyone watches them go." -Jodi Picoult
One of the toughest things to predict is where our galaxy's next supernova will occur. The smart bet is that it will be a massive star, 20 times the Sun's mass or more, as more than 80% of the Universe's supernovae are of the Type II…
esiegel | February 27, 2016"The bedrock nature of space and time and the unification of cosmos and quantum are surely among science's great 'open frontiers.' These are parts of the intellectual map where we're still groping for the truth - where, in the fashion of ancient cartographers, we must still inscribe 'here be dragons.'" -Martin Rees
We know the Earth is an almost-perfect sphere, yet maps of it always stretch it down to a two-dimensional surface. Outer space, too, when we look at it, offers views that extend deep into the cosmos in all directions, also on a sphere. But if you want to make a map of the Universe…
esiegel | February 22, 2016"The wonder is, not that the field of stars of so vast, but that man has measured it." -Anatole France
If you could gather 250 million times as much light as your eye, and improve your resolution by several orders of magnitude, you just might be able to see what the Hubble Space Telescope can. By extending down into the near-infrared, and combining those observations with that from other great observatories like Chandra and Spitzer, we can probe the star-formation history of the Universe.
Image credit: NASA, ESA, the GOODS Team and M. Giavalisco (STScI/University of Massachusetts), of a…
esiegel | February 19, 2016"Mathematicians deal with possible worlds, with an infinite number of logically consistent systems. Observers explore the one particular world we inhabit. Between the two stands the theorist. He studies possible worlds but only those which are compatible with the information furnished by observers. In other words, theory attempts to segregate the minimum number of possible worlds which must include the actual world we inhabit." -Edwin Hubble
The combined work of many 20th century astronomers and physicists -- including Einstein, Slipher, Leavitt and Hubble -- led to the conclusion that the…
esiegel | February 18, 2016"Vision is the art of seeing what is invisible to others." -Jonathan Swift
If you want to look out into the Universe, all you need to do is gather the light it gives off. Unless, of course, there's something in the way. For about 20% of the sky, that's exactly the story for our own Milky Way galaxy, where the neutral gas and dust block most of the visible light everywhere we look, preventing us from observing the Universe beyond.
Image credit: ESO/B.Tafreshi, of the Milky way in visible light as seen from Earth.
However, this doesn't mean we have no options: the gas and dust might block…
esiegel | February 17, 2016“If the imprint is really due to gravitational waves from the big bang, then this is the type of cosmological discovery that comes along perhaps once every fifty years.” -Kip Thorne
Now that LIGO's successfully detected it's first gravitational waves — from two merging black holes — we know that we will find them in a variety of circumstances if we look in the right way.
Illustration of a fast gamma-ray burst, previously only thought to occur from the merger of neutron stars. Image credit: ESO.
While LIGO and its successors will be great for exploring high-frequency events like small black…
esiegel | February 16, 2016“The world communicates subtly. Most people don't hear or see the signs because they're so wrapped up in their day-to-day lives.” -Doug Cooper
If you wanted to see if a planet was inhabited in Star Trek, all you had to do was scan for signs of life. With current technology, that's really hard to do! We rely on cues from all across the electromagnetic spectrum to identify biosignatures, such as analyzing the atmosphere, land and oceans for molecular signatures.
This image from Sentinel-2A shows how Saudi Arabia’s desert is being used for agriculture. The circles come from a central-pivot…
esiegel | February 15, 2016"We are stardust, we are golden,
We are billion year old carbon,
And we got to get ourselves back to the garden." -Crosby, Stills, Nash & Young
When Charles Messier first began cataloguing nebulae, even globular clusters, just a few tens of thousands of light years distant, weren’t resolvable into individual stars. But thanks to the Hubble Space Telescope, we can see individual stars in other galaxies many millions of light years away.
Image credit: NASA, ESA and T.M. Brown (STScI), of background galaxies seen through the disk of Andromeda.
In a series of images taken from 2004-2007,…
esiegel | February 11, 2016"Ladies and gentlemen, we have detected gravitational waves." -David Reitze
More than 100 years after Einstein's relativity came out, one of its last great predictions -- the existence of gravitational radiation -- has been directly experimentally confirmed! The LIGO collaboration has observed two ~30 solar mass black holes merging together, producing a slightly less massive final black hole as three sun's worth of mass was converted into energy via Einstein's E = mc^2.
Image credit: R. Hurt – Caltech/JPL.
This type of event, although quite serendipitous for the LIGO collaboration, is…
esiegel | February 11, 2016"We stand on a great threshold in the human history of space exploration. If life is prevalent in our neighborhood of the galaxy, it is within our resources and technological reach to be the first generation in human history to finally cross this threshold, and to learn if there is life of any kind beyond Earth." -Sara Seager
25 years ago, there were no planets known around Sun-like stars other than our own. Just 5 years ago, there were no rocky planets known around Sun-like stars other than our own. And today, we don't have any direct images of those rocky worlds potentially suitable for…