First it was there, then it wasn’t, and now it just may be back again: the first exoplanet directly observed orbiting a normal star, Fomalhaut b, has had quite a ride.
[This post has a bit of detail to it, so here's the tl;dr version: new analysis shows an object orbiting the star Fomalhaut may actually be a planet, enveloped in a cloud of dust. We can't for sure it exists, but we can't say it doesn't, either! Earlier claims of it not existing may have been premature. Also, at the bottom of this post is a gallery of direct images of exoplanets.]
First a brief history. In 2008, astronomers revealed huge news: they had successfully taken images of planets orbiting other stars. Up until then, the only evidence we had of exoplanets was indirect, either by their tugging on their stars which affects the starlight, or by having them pass between their stars and us, dimming the starlight.
But, along with Gemini telescope pictures of a family of planets orbiting HR 8799, Fomalhaut b was the first planet ever seen directly, as a spark of light in a picture. Here is that historic shot:
It’s Sauron’s eye! [Click to embiggen.]
The object is labeled. It doesn’t look like much, but the important thing to note is that it moved between 2004 and 2006 (see picture below), and it was definitely in both images taken two years apart. That means it wasn’t some bit of noise or detector error. Moreover, the movement was consistent with what you’d expect from a planet. Not only that but the star Fomalhaut is surrounded by a vast ring of dust – Sauron’s eye – and the inner edge of the ring is sharp. That’s what you would expect if a planet was orbiting inside the ring; its gravity sweeps up the dust on the inside of the ring. Given the brightness, we were looking at an object with a few times Jupiter’s mass, much smaller than a star, so definitely a planet.
All in all, it looked good, and it looked real.
Then, in early 2012, some astronomers threw a Pluto-esque wet blanket on the news. A planet that big should be bright in the infrared. Fomalhaut is a youngish star, only a few hundred million years old. Any planet more massive than Jupiter should still be hot, radiating away the heat of its formation. They looked for it in the infrared, and it wasn’t there.
To make things worse, they found that if you extrapolate the orbit of the supposed planet using its movement, it should cross the ring. That’s bad, because its gravity would disrupt the ring after a few million years tops. The ring is there, so that planet means the planet must not be.
Their conclusion: this object is a clump of dust, a cloud, orbiting the star. That fits the data, and a planet doesn’t. Cue the sad trombone.
But wait! We’re not done!
One of the most amazing objects in the sky is the Helix Nebula, an expanding cloud of gas and dust surrounding a dying star. This type of object is called a planetary nebula, and it’s formed when a star a bit more massive than the Sun turns into a red giant and blows off its outer layers. These expand away, and eventually the hot core of the star is exposed. This floods the gas with ultraviolet light, causing it to glow pretty much like a neon sign*.
The Spitzer Space Telescope and GALEX combined their forces to observe the Helix Nebula, and what they see is simply stunning:
Oh my. [Click to ennebulenate, or grab a 6000 x 6000 pixel version.]
GALEX sees in the ultraviolet, so it’s sensitive to the light coming from the central star and the hot gas reacting to it (colored blue in the picture). Spitzer sees in the infrared, so it detects warm gas and dust (red, yellow, and green). Where you see pink is where the nebula is emitting both IR and UV. [Note: some of the outskirts of the nebula were beyond Spitzer's field of view, so images from the infrared observatory WISE were used there to match the GALEX field.]
One of the most interesting features of this nebula is the collection of long, comet-like "fingers" you can see throughout the structure. These are where denser clumps of material are boiling away under the intense UV radiation of the central star, blowing out long tails away from the center like spokes in a wheel. Some of those tails are trillions of kilometers long!
Despite being one of the closest planetary nebulae in the sky – a mere 700 light years away – I’ve never seen the Helix through a telescope. Why not? Because it’s so big! The light from the gas is spread out over an area in the sky the size of the full Moon, dimming it considerably. Maybe someday I’ll be at a dark site with a big ‘scope, and I’ll see this fantastic bauble with my own eyes… but it won’t look like this picture. Our eyes see only a small slice of the electromagnetic spectrum. They serve us well in our daily lives, but the Universe itself sends out information in every direction to which we’re blind.
That is, until we used our limited brains to build devices like Spitzer and GALEX that expanded our viewpoint. And that’s what science does: removes the scales from our eyes, allowing us to see what the cosmos itself is showing us.
Image credit: NASA/JPL-Caltech
* I’m simplifying here a bit. If you want more in-depth info on what happens as a star like this dies and glows like some great gaudy celestial Christmas ornament, read this post about the Helix I wrote a while back.
Pretty much every picture of Saturn sent back home from the Cassini spacecraft is devastatingly gorgeous, but it’s confession time: I prefer the greyscale ones to the pictures in color.
Why? Because this:
Holy ringed gas giant awesomeness! [Click to encronosenate.]
This shot was taken earlier this year, in June, when Cassini was about 3 million kilometers from the planet. Saturn has a thick haze above its cloud tops, obscuring much of the details of the clouds below (one of the main reasons it doesn’t sport the same spectacular cloud bands as its big brother Jupiter), but this image was taken using a near-infrared filter – just outside the normal range of human vision (centered at 752 nanometers, for those who want details) – that can see some light that gets through the haze. The white spots and elongated features are the tops of clouds of ammonia, some of which are thousands and even tens of thousands of kilometers long.
I love the angle on this picture. Cassini was south of Saturn’s equator, looking north. The northern hemisphere of the planet is edging toward summer right now, so the Sun is shining down on the rings, projecting their shadow on the southern hemisphere. We see the rings here from the unlit side, so they look a bit darker than you might be used to. However, since they’re made almost entirely of water ice, they’re transparent and scatter sunlight, so you can see them even from their shadowed side.
As a bonus, you can also see the tiny moon Enceladus on the lower left. Of course, when I say "tiny", I mean the size of my home state of Colorado.
This picture is jaw-droppingly beautiful, and I think a big part of that is that it’s greyscale (what some people call "black and white", which isn’t accurate since we see lots of shades of grey). While color images can be stunning, there is something about the contrast and chocolaty smoothness of greyscale that makes pictures like this more magnificent, more dramatic, and more brooding. I don’t know what it is – it’s the same phenomenon that happens with old movies, too – but for me it’s certainly a powerful effect.
As if Saturn needs any help.
Image credit: NASA/JPL-Caltech/Space Science Institute
According to my software, this blog post you are reading is the 7000th article I have published on the Bad Astronomy Blog.
That’s a lot of words. It’s also a lot of astronomy, geekery, science, antiscience, web comics, puns, embiggenates, and "Holy Haleakala!"s (61, to be exact, plus this one to make 62).
I am generally not one to wade into maudlin celebrations of arbitrary numbers, so instead I’ll celebrate this milestone by showing you something appropriate: the North America Nebula, taken by Mexican astronomer César Cantú.
[Click to encontinentenate.]
Why is this appropriate? Because the New General Catalog of astronomical objects – familiar to and used by astronomers across the planet – lists it as entry number 7000.
And it should be obvious why it’s named as it is.
Of course, I can’t leave you with just a pretty picture. This nebula is something of a mystery; we don’t know how big it is or how far away it lies. In the sky, it’s very near the star Deneb – which marks the tail of the swan constellation Cygnus – and Deneb is a massive, hot, and luminous star. It’s possible the gas in the nebula is glowing due to the light from Deneb; if so NGC 7000 is about 1800 light years away and over 100 light years across.
It’s the site of furious star formation, too, with stars being born all along the bright sharp region which look like Mexico and Central America. The "Gulf of Mexico" region – the darker area with fewer stars – is actually the location of thick interstellar dust that blocks the light from the stars behind it. Visible light, that is; the dust glow in the infrared, so if you look at it with a telescope that sees IR like the Spitzer Space Telescope, what is invisible becomes ethereally visible:
This mosaic shows the North America Nebula in different wavelengths of light: in the upper left is visible light; the upper right is visible plus infrared, so you can see the two together; the lower left shows infrared light from 3.6 to 8 microns (roughly 5 – 11 times the longest wavelength the human eye can detect), and the lower right is similar but going out to 24 microns, over 30 times the wavelength we can see. The visible light images show the gas, while the infrared show not only the dust, but the warm spots where stars are being born, their new light penetrating the surrounding cocoons of material, reaching across space, and finally ending its journey here on Earth where we can detect it and learn from it.
I’ve struck upon many ideas for this blog over the past seven years, six months, and one week I’ve been writing it, but one of the most important is this: not everything is as it seems. Whether it’s someone’s opinion, a "fact", a picture, an argument, or even a vast sprawling cloud of gas and baby stars a thousand trillion kilometers across, this much is what astronomy and critical thinking has taught me: What you see depends very much on how you see it. And if you want a more complete picture, something that ever-approaches reality, you must view the Universe with different eyes and with an open, but trained mind. Only then will you not get fooled, and not fool yourself.
Thank you honestly and sincerely to everyone who’s been along with me this far into the ride, here on my 7000th milestone. There’s still a long way to go, of course, but it’s the journey itself that’s so much fun!
Image credits: César Cantú; NASA/JPL-Caltech/L. Rebull (SSC/Caltech)/D. De Martin
The James Webb Space Telescope – NASA’s successor to Hubble – recently reached a pretty big milestone: all of the segments of its primary mirror have completed construction, and are ready to be handed over to NASA.
JWST isn’t your average ‘scope. Instead of a single, monolithic mirror, it will have 18 hexagonal segments that will fit together, working as a unit to focus infrared light from distant astronomical objects. Each segment is about 1.5 meters across, and will have actuators behind them (think of them as very accurately tunable pistons) to control exactly how the submirrors are aimed. On the front, each mirror is coated in a very thin layer of gold, which is an excellent reflector of IR light.
The mirrors were made at the Ball Aerospace facilities in my hometown of Boulder, Colorado. Ball threw a celebration to mark the mirrors’ completion, and invited a few press folks along. That included me! We went on a tour, and saw one of the mirrors – it was in a "clean room" to keep dust and other contaminants out. But we could see it through a door… and here it is:
Yes, that’s me reflected in one of JWST’s flight mirrors! That was pretty cool. [Click to embiggen.]
Looking a picture of a mirror can be difficult when you’re trying to see the mirror itself. Here’s another shot that makes it more obvious.
The mirrors is tilted up, and the dark band running through it is the reflection of the top of the stand it’s mounted in. Their mirror itself is the gold hexagon. I got a good look at it, and it’s no small thing for me to say its the cleanest mirror I’ve ever seen. I’ve been around a few ‘scopes in my time and their mirrors always have some schmutz on them. This had none.
The figure of each mirror (the technical term for the shape of the surface) is incredibly accurate: the bumps in the surface are on average smaller than 25 nanometers. A nanometer is a billionth of a meter… to give you an idea of how small this is, a typical human hair is 400 times thicker than the deformities in the mirror. As one person mentioned to me while we were gawking at the facilities, if a bacterium fell on the surface, it would far and away be the biggest thing on the mirror.
So yeah, these things are smooooth.
The mirrors need to be this smooth to accurately reflect light. Any nonconformity would scatter light a little bit, messing up the telescope’s resolution. I’ll add that mirrors like this – the size they are, made of beryllium, figured to this accuracy – have never been accomplished before. And that’s only part of it, since of course all 18 mirrors must act as one once JWST is in orbit.
We were shown a room with the tanks containing the completed mirrors, laid out on the floor in the same configuration they’ll be in the telescope itself:
On July 5, 2012, the European Space Agency launched the Meteosat Second Generation-3 (MSG-3) weather satellite into a geosynchronous orbit about 40,000 kilometers above the Earth. It has several cameras on board, including the Spinning Enhanced Visible and Infrared Imager (SEVIRI) that takes (duh) visible and infrared pictures in 12 different wavelengths (colors). The first image from that camera was just sent back, and it’s an incredibly beautiful shot of our home world:
[Click to enterranate, and holy cow do you want to.]
There is nothing about this picture I don’t love. I think my favorite part is South America, on the left, coming out of night time and into the dawn. But the chains of clouds over Africa are a close second.
SEVIRI has a resolution of 1-3 kilometers, and can take these amazing full-disk shots of Earth. It also has a detector that can measure the amount of sunlight reflecting off the Earth as well as infrared light radiated by the Earth, which are critical measurements needed to better understand global warming. Interestingly, it also has a search and rescue transponder that acts as a relay for emergency distress signals.
MSG-3 is the third of four second generation METEOSAT satellites launched by the ESA; a third generation is even now being designed.
Everything this and the other MSG satellites do is important to our understanding of weather and climate, of course, and I’m glad these are being built and flown. But it doesn’t hurt to also just marvel at the stunning pictures they send us.
Image credit: Eumetsat
Well, what can I say about this devastating and jaw-dropping picture of our nearest spiral neighbor, the Andromeda Galaxy?
[Click to massive chainedmaidenate. Do it!]
Well, I could start with HOLY HALEAKALA!
This image is a collection of 11 separate observations of Andromeda taken by NASA’s GALEX satellite. Launched in 2003, GALEX (which stands for Galaxy Evolution Explorer) scans the sky in ultraviolet light, specifically targeting galaxies. Hot stars produce UV light, and so does the gas it illuminates, so by looking in the ultraviolet astronomers can learn about how galaxies are constructed. In the decade since its launch, GALEX has been phenomenally successful, cataloging hundreds of millions of galaxies, some as far as ten billion light years away!
This image of Andromeda is simply stunning. It’s comprised of two colors: what you see here as blue is higher-energy ultraviolet light, and red is lower energy (closer to the kind of light we see). Right away you can see that objects emitting the higher-energy UV are confined to the spiral arms, and lower-energy emitters are spread out across the galaxy. That’s exactly what I would expect: massive stars, the kind that really blast out UV, don’t live very long. They’re born, live out their short lives, and die (as supernovae) pretty much near the spot where they formed, which is in spiral arms. Lower mass stars live long enough to gradually move away from their nurseries, populating the rest of the galaxy.
Also, star formation at the very center of the galaxy probably occurred long ago and shut down, so we don’t see many or any massive stars there.
One thing I didn’t know is that the arms of Andromeda are more like rings! The galaxy is at such a narrow angle that it’s hard to tell, but if you trace the blue emission, the pattern does look more like a ring than a spiral. This jibes with earlier images in infrared taken by Spitzer Space Telescope (which I’ve inset here) and a huge and incredibly beautiful newer one taken with ESA’s Herschel far-infrared telescope (and OMFSM you want to click that link).
From what I’ve read, it’s not clear why the spiral arms appear to be more ring-like. Which I love. Why? Because Andromeda is the nearest big spiral galaxy in the sky, a mere 2.5 or so million light years away. It’s easily visible to the naked eye from a dark site, and I’ve seen it myself countless times using my own eyes, binoculars, and telescopes ranging from small ones up to Hubble. Yet there it is, in all its huge and obvious splendor and beauty, still able to surprise me. That rocks.
And a note about GALEX: NASA recently handed off its operations to Caltech, a very unusual move. The satellite was put into standby mode in February, and I was worried it would be shut down permanently. However, Caltech signed a three-year agreement with NASA — while NASA still owns the satellite, Caltech will now be in control of GALEX’s science mission, managing and operating it. At the end of the agreement it can be renegotiated if GALEX is still in good operating condition. This is an interesting idea, and I’m not sure how I feel about it. I love that GALEX gets to continue operations, but handing off science missions to private groups makes me a little uneasy. In this particular case I think it’s fine — Caltech is a research institute after all — but the precedent may have unforeseen consequences. We’ll see.
Still and all, it’s good to see new life breathed into an important and wonderful instrument like GALEX. I certainly hope it will continue to produce cutting-edge science for years to come… as well as amazingly beautiful images like this one.
Image credit: NASA/JPL-Caltech
- The cold arms and hot, hot heart of the fuzzy maiden
- The first spectacular views of the sky from WISE
- A Swift view of Andromeda
- Andromeda’s warm glow
- Andromeda: born out of a massive collision?
Orbiting our galaxy in the lonely depths of intergalactic space, 160+ globular clusters are among the oldest structures we know. They’re composed of thousands, sometimes hundreds of thousands, of stars, all held together by their mutual gravity. I always think of them as beehives, with the stars buzzing around on orbits all tilted willy-nilly.
The European Southern Observatory just released this picture of the globular cluster M55 using the VISTA telescope., and it’s very pretty:
[Click to englobulenate, or grab the 6Mb 3k x 3k pixel version!]
Honestly, there’s not a lot of science I can add to this that I haven’t written about a bazillion times before (see Related Posts, below). M55 is 17,000 light years away toward the galactic center, which is relatively close as these things go. It’s big, 100 light years across, so from Earth it looks to be roughly 2/3 the size of the Moon. In this unusual picture by VISTA, we’re seeing it in infrared — at 1 micron (colored blue in the picture) and 1.5 microns (colored red), so stars that look red are really much cooler than the Sun.
But other than that, it’s just another run-of-the-mill globular. Which is remarkable enough! And you know what: despite their clunky name, there’s no such thing as an ugly globular cluster. That’s reason enough to share this lovely picture.
Image credit: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit
Since the first planet was discovered orbiting another Sun-like star in 1995, nearly 800 more have been discovered. Only a handful have been directly detected: most are discovered by their influence on their star, either by tugging it or blocking its light as the planet orbits (at the bottom of this post is a gallery of images of exoplanets detected in these ways). But some have been directly seen: either glowing by their own light, reflecting that of their star, or — ironically — seen when they’re not seen.
Say what? OK, this takes a sec to explain, but it’s cool.
The star 55 Cancri hosts at least 5 planets. Located 40 light years away, it’s one of the closer planetary systems, and has been intensely studied. One of the planets, 55 Cancri e, is bizarre: it’s twice the diameter of the Earth and has 8 times our mass. It’s thought to have a dense core surrounded by water… but Earth-like it ain’t. It orbits its star in a very tight orbit, circling it once every 18 hours. It’s so close to the star that the surface temperature is probably around 1700°C — or 3100°F! That’s hot enough to melt lead.
So yikes. If it does have water, it’s in the form of a weird super-heated steam only held to the planet due to its strong gravity. Even then, the atmosphere may be boiling away like a gigantic comet. So again, this isn’t like Earth at all. Even Venus isn’t this unpleasant, and on Venus it rains sulfuric acid.
Anyway, an object at that temperature will glow in the infrared, quite strongly. If it were sitting all by itself in space, it would be easy to see. However, it’s sitting next to a star which is millions of times brighter, making it a significantly more difficult target.
… but not impossible. Read More
In 2003, NASA’s Spitzer Space Telescope launched into space to begin a mission to observe the heavens in infrared. That kind of light is emitted by warm objects, so its main imaging camera — called IRAC, for Infrared Array Camera — had to be cooled using liquid helium, or else the infrared light it gave off would interfere with its own observations!
This type of coolant leaks away slowly, and after about five and a half years — a much longer period of time than originally hoped, which was a bonus — the liquid helium was finally depleted. However, this didn’t end the mission; instead it marked the beginning of the "warm phase". Observations could still be made, though only with some of the detectors that weren’t so severely affected by the raised temperature.
That was in May 2009. Spitzer has now been running warm for 1000 days, and to celebrate that milestone the folks running the observatory released their favorite 10 Spitzer IRAC images. Over the years I’ve featured half these images on the blog (see the list below), but I have no idea how I missed this amazing shot:
Isn’t that cool? Well, so to speak. Haha. Because of the warm mission, you see. Ha ha.
But what is it? Just off the top of the picture is a young star. It’s a newborn, a mere baby, probably less than a million years old, and like human babies it tends to spew matter out of both ends. In this case, the star’s rapid spin coupled with its intense magnetic field create two powerful jets of material that blast away from its poles at speeds of up to 100 kilometers per second! What you’re seeing here is one of those jets as it plows through a cold cloud of gas and dust. The shape may be due to the material in the jet following the twisted magnetic field lines, or it may be formed as the shock waves emanating from the interaction become unstable, a bit like breaking waves from a ship ramming through the water at high speed. Either way, it looks for all the world — the galaxy! — like a rainbow tornado.