Bad Astronomy
The entire universe in blog form

Sept. 3 2016 9:00 AM

Time-Lapse: Hades Exhales

Getting an email from Harun Mehmedinovic is always good news: It means he has a stunning new time-lapse animation of the night sky he’s made.

His most recent note to me did not disappoint: It’s an ethereally beautiful video showing the heavens above the geysers and hot springs of Yellowstone, and holy wow. Watch:

It’s a testament to Mehmedinovic’s skill that while I’m usually riveted to the sky in these videos, in this case I hardly saw it. I was too busy holding my breath watching the incredible landscape.

I was particularly interested in the geysers. The plumes looked odd to me, like they were superimposed over something dark … and then it struck me that what I was seeing were the shadows of the trees on the plumes as they billowed by! That was a fun moment; that split second when you feel off kilter, then suddenly understand what you’re seeing. It’s a little slice of scientific inquiry (the “aha!” moment that happens all too rarely) encapsulated in art and even more science.

I’ve never been to Yellowstone, and that’s an oversight I’m keen to fix. I very much want to see the boiling pits of minerals and chemicals brought to the surface by geologic activity there, and watch the dark sky through a plume for myself. I do so love geology, especially when astronomy is thrown into the mix as well.

By the way, Mehmedinovic does this as part of the Skyglow project, a crowdsourced effort to bring attention to the effects of light pollution on dark skies in North America. I urge you to watch the other videos he’s done for this (especially the one of Dry Tortugas Park), as they are all amazing, and truly deliver the beauty of the sky and the Earth.

Sept. 2 2016 9:00 AM

Beams From the Setting Sun Cast Their Way Across the Sky

I am endlessly fascinated by phenomena in the sky, whether they occur billions of light-years away, or just above our heads. I’m not sure if that’s a byproduct of being an astronomer and looking up all the time, or if I just love all this stuff and up is the direction they happen to be in.

Either way, I’ve seen a lot of amazing things in the sky. Still, the photo above, taken by my old friend (and astronomer) Rob Sparks, took me by surprise! I don’t think I’ve ever seen anything quite like it: a wide-angle (“fish eye”) view of the sky showing one of my absolute favorite phenomena, crepuscular rays.

That’s the fancy name for the beams of light you see fanning out from the Sun, on a partially cloudy day. They are literally the shadows of clouds falling on haze or other junk floating in the air, making dark bands that interrupt the usual flow of the sunlight.

Here’s the thing, though: Even though they appear to fan out, they’re actually parallel! It’s perspective that makes them appear to diverge. At sunset, for example, the shadows start physically far away, in the air on the horizon. That can be hundreds of kilometers away, but the air overhead is only a few kilometers up. Things far away appear smaller, so the distance between the rays is small. But the part of the shadows over your head are much closer, so the distance between them is bigger. That gives them the illusion of divergence.

But there’s more. If there are enough particles in the air, at sunset these rays can stretch a long way across the sky, and sometimes they reach all the way across. As their distance increases from you, they appear to reconverge on the horizon opposite the Sun (called the anti-solar apex). When they do this, they’re called anticrepuscular rays.

more crepuscular rays
Looking east at sunset, the rays converge again.

Rob Sparks, used by permission

That’s what you’re seeing in Rob’s photo. The distortion added by the wide angle lens gives it an added layer of weirdness, too, especially since that one dark ray goes right through the middle, and isn’t as affected by the lens’s distortion as the ones near the horizon. In the second photo above (showing just the anticrepuscular rays as he looked east) the distortion is less, and you get the view you’d more normally see by eye.

Rob took these in Arizona on Aug. 11, when the sky was a beautiful blue, the setting Sun lit the eastern clouds magenta, and the half-full Moon hung in the sky. You might be surprised the Moon looks so small, but in reality it’s pretty small in the sky. How small it actually is might surprise you, too.

I’m glad Rob let me know about these photos; they’re lovely and interesting. He takes lots of pictures of the sky, and if you follow him on Twitter, you’ll get to see them too.

Of course, if you look up every now and again you can see this stuff for yourself. That’s a good idea, too.

Sept. 1 2016 11:29 AM

SpaceX Falcon 9 Rocket Explodes on Launch Pad During Fueling

Thursday morning at around 9 ET, a SpaceX Falcon 9 rocket exploded while being fueled up for an engine test firing at NASA’s Kennedy Space Center in Florida. At this time, I have no info on what happened, except that the explosion occurred three minutes before the test was scheduled. The rocket was uncrewed and no one was near the pad, so no one was injured. However, it appears that the payload, an Israeli communications satellite called AMOS-6, was lost. The launch was to have been on Saturday.

My colleague Susan Matthews at Slate has more information.

Update (Sep. 1, 2016 at 19:00 UTC): Video of the explosion has been released by USLaunchReport.com:

This is bad, have no doubt. It will delay the launch schedule for SpaceX for months to come, including the first flight of the Falcon Heavy, a huge rocket that was supposed to launch late this year, and the first flight of a previously used first stage booster that relanded after being used in a launch. There have been 28 Falcon 9 launches with two failures (if you include this one, and again we don't know the cause, and it wasn't during launch).

I suggest following SpaceX and Eric Berger on Twitter for updates. I'll post more information when I can.

Correction, Sept. 1, 2016: In the original headline I wrote the rocket exploded on a test stand. It was actually on the LC 40 launch pad. Parts of the pad were damaged as well.

Sept. 1 2016 9:00 AM

A Monster Galaxy Hiding in Plain Sight

Not too far away in cosmic terms—about 250 million light-years—lies a monster. The thing is, we’ve known about it for a long time, but we didn’t know what it truly was because it was hiding its true nature from us.

It’s a galaxy, named UCG 1382. It was discovered decades ago, and in pictures taken using visible light telescopes it looks like a fairly typical elliptical galaxy. It’s relatively isolated, with just a handful of much smaller galaxies nearby, and doesn’t seem to be doing much. Astronomers didn’t ignore it, exactly, but there wasn’t much there to excite them, either.

That is, until a team of astronomers happened to look at ultraviolet images of it taken by the GALEX space telescope. What they saw was very surprising: a set of spiral arms extending well beyond the visible part of the galaxy! Right away that’s pretty dang weird; spiral arms are usually very bright in optical light because that’s where stars are born, including massive, luminous ones. But this also means the galaxy was larger than first thought. Much, much larger: The diameter across the arms is 500,000 light-years, five times the size of our home galaxy, the Milky Way!

Then it got even weirder: They investigated the galaxy with the Very Large Array, a set of radio telescopes in New Mexico. What they saw was nothing less than shocking. The radio telescopes detected hydrogen gas going out even further from the center, which means this galaxy is nearly 720,000 light-years across!

It’s not just huge. It’s a monster.

These new observations show that, far from being some uninteresting galaxy, UGC 1382 is actually one of the biggest known galaxies in the Universe.

UGC 1382
Big, bigger, biggest: UGC 1382 in optical light (left), optical plus ultraviolet (middle), and optical+UV+radio (right).

NASA/JPL/Caltech/SDSS/NRAO

It’s in a class known as Giant Low Surface Brightness, or GLSB, galaxies. Only about a dozen are known, including the previously thought biggest, Malin 1, which is about the same size as UGN 1382. The thing is, UGC 1382 is much closer than Malin 1 (250 million versus 1.2 billion light-years), making it far easier to study.

And when the astronomers studied it, it kept getting weirder. For one thing, it doesn’t have nearly as many stars as you’d think for such a huge beast. Its total mass of stars is about 80 billion times the mass of the Sun, which is much less than the Milky Way! Even adding in all the gas in the galaxy, its total mass is about 100 billion solar masses, 1/10th of the Milky Way’s mass. That explains why it’s so faint; there isn’t a lot of there there, and it’s spread out over a lot of real estate.

It also has a huge halo of dark matter, the unseen and still mysterious substance that outnumbers normal matter (the stuff we’re made of, like protons, electrons, and neutrons) by about 5 to 1 in the Universe. The galaxy has about 2 trillion times the Sun’s mass of dark matter, which means UGC 1382 has a dark matter to normal matter ratio of 20:1. That’s really high.

And there’s one more weirdness: The outer parts of the galaxy (the gigantic disk with the arms in it) appears to be older than the inner part. That’s the opposite of “normal” spiral galaxies; in general the inner part is made of very old stars, because star formation there shut down early in the life of the galaxy, while it continues on in the spiral arms. Apparently UGC 1382 didn’t get that memo.

So how does a GLSB galaxy like UGC 1382 form? Galaxies like ours got big by eating other galaxies. Smaller ones get caught by bigger galaxies’ gravity, get torn apart, and fall into them. Sometimes you get collisions between bigger galaxies, too; we’ll be colliding with the massive Andromeda galaxy in a few billion years, forming one huger galaxy with twice the mass.

But that isn’t the case with UGC 1382. A collision like that would disrupt the spiral disk. But that’s the oldest part of the galaxy, so it’s unlikely it would still be around after the giant train wreck of a galactic collision.

What the astronomers posit is that it grew slowly by snacking gently on much smaller gas-rich dwarf galaxies. The events wouldn’t be so violent, so it would be able to maintain its disk (the massive dark matter halo is also helpful in maintaining the disk structure; it acts as a stabilizing influence on it). If the dwarf galaxies were old, that would explain the inside-out age problem, too. Those smaller galaxies would likely be pulled apart and distributed in the outskirts of UGC 1382, making it look older than the downtown region.

Also, remember that UGC 1382 is isolated, with no big galaxies nearby, so it’s unlikely to have big galaxies to collide with in the first place. In fact, all GLSB galaxies appear to be relatively isolated, so this is apt to be a key characteristic for them.

This is all a bit staggering. These monster galaxies weren’t even discovered until relatively recently, despite their ridiculous size. The problem is that the biggest parts of them, their disks, are very faint, making them hard to see. UGC 1382 shows us that many more could be hiding in plain sight, right in front of us.

It’s ironic that the biggest known single objects in the Universe are so hard to find, or at least so hard to identify. The cosmos is usually pretty good about letting us understand it, showing us a dramatic array of objects that all obey the laws of physics, allowing us to tease out information.

But no one ever said it would make it easy on us.

Aug. 31 2016 9:00 AM

No, We Almost Certainly Did Not Detect an Alien Signal

The internets are buzzing with news that a Russian radio telescope detected a signal from a nearby Sun-like star and that it may be from an alien civilization.

I’ll ask you to read the title of this post again before I continue.

OK, got it? Here’s the thing: If we did detect a strong signal that had all the earmarks of an alien civilization, you’d be hearing SETI astronomers (and people like me) singing it from the rooftops. This ain’t that.

Here’s another thing: The signal is real, and may very well be from an intelligent civilization. That civilization, however, is us.

The signal appears to come from a part of the sky containing the star HD 164595, a star very much like the Sun, but located about 95 light-years away. It’s older than the Sun, likely a bit more than 6 billion years in age (the Sun is about 4.5 billion years old). It’s known to have at least one planet, what’s likely to be a gas giant with about Neptune’s mass, orbiting the star every 40 days. It may have other planets, but if so we haven’t detected them yet.

The signal was detected in May of 2015 and was a relatively weak but well-detected blip of energy at a wavelength of 2.7 cm (or a frequency of about 11 GHz if you prefer). The problem is knowing what it came from. The radio telescope, called RATAN-600 and located in Russia, has a relatively large beam pattern (you can think of it as the telescope’s ability to resolve objects that are close together). A lot of stars are in the area of the sky from which the signal originated, so it may not have come from HD 164595 at all. That’s just a guess on the part of the astronomers.

If it did come from that star, it was a powerful burst! My friend and SETI astronomer Seth Shostak calculates that at best it would take the entire human energy consumption rate to replicate it.

But the signal detected was the only signal detected. Only the one beep was seen, and despite SETI telescopes looking again and more carefully at the star, no other signal has been found. That seems like an odd course of action for aliens.

So what was it? It may have been natural in origin, a weird radio burst from a star or galaxy in the telescope’s field of view at the time. But it may have been unnatural: Astronomer Yu V. Sotnikova of the Special Astrophysical Observatory in Russia issued a statement saying the signal is likely “of terrestrial origin.” However, no other evidence for this was given. The frequency of the signal is near those used by the military and other human endeavors, so perhaps that’s what was meant by the statement.

Given all this, that seems the most likely scenario. I can’t say much about this for sure: It may or may not have come from that star, it may or may not have been natural, and it may or may not be from a military satellite or radar. But if I were a betting man—and I am— I’d wager heavily this was not from aliens.

I know, I’ve had to say something like this many times in the past few months, but that doesn’t make it any less true. If and when we ever do detect an alien signal, I trust my friends and colleagues at SETI will let us all know what they know as soon as they know. Until then, well, we’ll just have to keep looking. We’ll never find anything if we don’t look.

Aug. 30 2016 9:00 AM

Astronomers Find Three Exploded Stars Nested Like Russian Dolls

When a star explodes, it’s a catastrophic event on a cosmic scale. The amount of energy released is beyond the grasp of our puny human minds; in a few seconds it blasts out as much energy as the Sun will over its entire lifetime.

Needless to say, you don’t want to be anywhere near a supernova. So what would it be like to be near three of them?

If there are any aliens perusing the skies in the nearby galaxy M33, they got their chance. Astronomers have found the expanding debris from not one, but three previously unknown supernovae. Better yet: The spherical shells of gas hurled outward by these explosions are concentric, centered on the same point in space, which means all three stars were very close to each other when they let go.

This weird triple supernova was found using a technique that specifically looks for rapidly moving gas. It involves a special kind of spectrograph that breaks the incoming light for the sky into very narrow slices of color. The resulting spectrum can reveal a lot of information about an object, including its composition, speed through space, and more.

In this case the spectrograph can create a spectrum for every point in the sky in the telescope’s field of view. For a supernova remnant (the expanding gas from the explosion), some of that gas will be moving toward us (the gas on the near side of the explosion) and some away from us (on the other side of the explosion). The gas heading toward us will have its spectrum shifted toward shorter wavelengths (called blue shift), while the gas moving away will be shifted toward longer ones (red shift).

By mapping these blue and red shifts, the astronomers could see the extent of the expanding gas and how fast the gas is moving. To their surprise, they found the three rings of gas all centered on the same spot, all with different sizes, and moving at different speeds.

They conclude that there must have been a cluster of stars in M33 that had three stars in it of roughly the same age and mass. Judging from how fast the gas is expanding and the size of the rings, the stars blew up 114,000, 40,000, and 21,000 years ago. The bubbles of expanding gas are 140, 52, and 41 light-years across, respectively. Mind you, massive stars live for a few million years, so these three stars blew up pretty close together in time compared to their age. How long a star lives depends on its mass, which is why it seems likely they were born at the same time with the same mass, too.

Each bubble of expanding gas has swept up a lot of material consisting of gas and dust between the stars, adding to its bulk. As I read the paper, I was surprised that the youngest explosion was able to do this. When a star explodes, the gas blasts outward and sweeps up a lot of the material around it like a snowplow. After the first explosion cleaned everything up, I wouldn’t expect there to be enough left for the latest of the three explosions to pick much up.

The astronomers who made the observations expressed the same surprise. They surmise that dense knots of cold gas, which are common in regions of active star formation, were disrupted and boiled off in the first and second explosions, basically evaporating and replenishing the gas swept up. That new material was then plowed up in the subsequent blasts.

Back when I was doing my Ph.D. work, and later on Hubble (as well as when I was writing outreach materials for other NASA missions) I often wondered what it would look like if several supernovae went off near each other around the same time. I wasn’t sure it would ever happen, but these observations look to show exactly this. M33 is less than 3 million light-years away, which is in our back yard as galaxies go; in fact it’s a small spiral that’s part of what we call the Local Group, a loose collection of a few dozen galaxies including ours, the Andromeda Galaxy, and a bunch of dwarf galaxies. That means that this strange matryoshka doll of supernova remnants can be studied in more detail, which is good news.

It also means something else: If we find one in a nearby galaxy, then it’s likely to be a common phenomenon. I hope the search continues and is successful in finding more of these. The Universe is a weird and wonderful place, and a new category of objects is a delight to astronomers … even when they’re the result of some of the most violent events that Universe is capable of.

Tip o’ the neutron star to Michael Krol.

Aug. 29 2016 9:00 AM

Grasping Climate Change

These are facts: Global warming is real, and almost entirely caused by human activities. Natural variability in temperature is minor compared with what we’re doing. This increase in temperature is causing the climate to change, in many ways that are not only predictable but actually observed. This in turn is causing other effects, like Arctic and Antarctic ice loss, sea level rise, coral bleaching, more extreme weather, and much, much more.

Again: Those are facts. The vast majority of scientists who have dedicated their lives to studying the climate agree on this.

And yet a small but vocal minority of people won’t accept that. Why? Some are sponsored by fossil fuel companies, the same ones who for decades have pumped money into disinformation campaigns, as well as politicians’ pockets. And of course some are ideologically inclined to dismiss science, or progressive politics (which has nothing to do with the science).

Still, some people honestly question the existence of global warming and its effects on the climate. Given all these facts, why do they do so?

Part of the problem—outside the general atmosphere of denial the media helps promote—is the scope and scale of climate change itself coupled with our puny brains trying to deal with it.

We humans have a miserable sense of scale. We see what’s immediately around us, and have difficulty extrapolating to the greater world. Even those of us who travel around the country and the world can still easily fail to grasp the scale of humanity’s presence. There are more than 7 billion of us! And billions of cars, millions of buildings, billions of houses, all of which use up energy and contribute to the emission of carbon dioxide.

But we can’t hold those numbers in our hands (why do you think we use the phrase “grasping a situation”?) and so our impact seems like it must be small.

But then look at the other side of the equation. The Earth is huge! So huge, again we can’t grasp it. Five hundred million square kilometers of surface area! Five quadrillion tons of air in the atmosphere! A hurricane is an unbelievable event, releasing as much energy as tens of thousands of nuclear bombs going off over a few days!

How could we possibly have an effect on a planet with scales like that?

And the answer is that we do have an effect, and it is small. But it never stops.

That can be hard to swallow, because time is long and our perception narrow. We have firm memories of recent experiences, fuzzier ones going further into the past, and dim ones going back decades.

And that is the true evil of climate change. It’s slow, and patient. It’s everywhere, but takes its time. It operates every day, but its effects don’t manifest for decades. Weather changes every day, every hour, and that noise washes out the signal of climate change.

Unless, that is, we too are patient, and keep our eyes on the long view. When we do, we see the trend, not the bumps and wiggles. This short, one-minute video frames it the best way I have ever seen: as a person walking a dog:

If we watch the trend, and not the wiggles, we see the impact of humanity on our planet. The temperature trend is actually quite clear now. And that trend is up.

As it will continue to be, unless we act. We put 40 billion tons of carbon dioxide into the air every year, and this is the root cause of all this. We can cut that back significantly if we decide to. It’s not easy, and it won’t be without cost, but it can be done. The alternative is to have the effects of climate change get more and more obvious, on shorter and shorter timescales.

What can we do? We can charge companies that put carbon into the air. We can rely on more renewable energies (solar and wind, of course, but we can also reopen the books on nuclear).

And the most important thing? We can vote.

The Republican Party has made it clear how they feel about climate change. Their official platform only mentions it a few times, and that’s to dismiss it, and their presidential candidate, Donald Trump, calls it a “hoax” and chose a denier as his energy consultant and another as his vice presidential pick. The Democratic Party platform talks about it much more realistically, categorizing it as a threat to our nation and our world. I have issues with Hillary Clinton’s climate change strategy, but those are minor to the point of nonexistent compared with the flat-out denial and active promotion of fossil fuels from the GOP. Accepting there’s a problem is step one, and even a slow approach is better than fueling the fire. Literally.

Look up your senators, your representative. Find out where they stand on this issue. Contact them, write a letter (that’s the most effective means of getting your voice heard), supporting them if they understand the reality of climate change, or briefly and politely letting them know how you feel if they don’t.

And if you hear someone denying climate change, may I humbly suggest searching this very blog for more info with which to give them facts, and links to more information? Other good sources include NASA’s climate site, NOAA’s climate site, Skeptical Science, DesmogBlog, RealClimate, and Climate Central.

It’s not too late. If we choose wisely, that is.

Aug. 27 2016 9:00 AM

Goaturday

Is Caturday still a thing? I don’t care, because it’s now Goaturday.

That is my goat, Jack Burton.* He is one of four goats we have chez BA, the others being Sam, Batman, and Clayton Forrester. They are all fun and cute and adorable, and you can find lots more pictures of them on my Instagram feed (for all my social media links, go to about.me). For example, here is video of me feeding them apples, and here is Jack yelling, “What what?”

I’m on travel right now and my wife sent me this photo of Jack to remind me of some of what I’m away from. It makes me homesick, but it also makes me smile that he’s such a dork, chewing with his mouth open. They’re all dorks and I miss them. But look at him! Look!

When I get home I will scratch them all on their heads and pat their bellies and they will in turn belch in my face and poop everywhere, because they are goats. That’s all as it should be.

*Because I know someone will ask: Here ya go.

Aug. 26 2016 9:00 AM

Venus and Jupiter Kiss This Weekend

There’s a real treat in the sky over the next few nights: Venus and Jupiter will be very close together. How close?

Very, very close. Closest approach (what astronomers call the appulse, but is more colloquially and commonly called a conjunction) will be on Saturday at 22:00 UTC (18:00 Eastern U.S. time), and at that time they’ll be an incredible four arcminutes apart. That’s only one-seventh the width of the full Moon on the sky!* In fact Jupiter appears half an arc minute across, so Venus will only be about eight times Jupiter’s diameter away!

That’s close. Close enough that they’ll barely be far enough apart to separate by eye. The simulated shot at the top of this post shows the view through a telescope at closest approach; you can see Jupiter, its moons, and Venus all together nice and snug.

Now for the not so great news: The two are only a little over 20° from the Sun, so they’ll be low over the western horizon by the time the sky gets dark after sunset. The good news though is that both are so bright they’re visible even while the sky is still bright, especially in binoculars. If you know where to look you can actually see them when the Sun is up, too! But that’s for folks with some experience; do NOT search for them with binoculars; the Sun is so bright it can physically hurt your eyes if you accidentally glimpse it through them.

Venus and Jupiter
In 2012, Venus and Jupiter passed each other, but this weekend's appulse is far tighter.

Guillaume Poulin, used by permission

The conjunction is cool not just because it’s pretty (and it is). It’s also rare. The planets orbit the Sun, moving at different speeds. They all stay in pretty much the same plane—it’s usually called the plane of the solar system—and we’re in it too, so the planets move more or less along the same path in the sky. But not exactly the same path, so they pass each other at various distances. A close pass is pretty rare and in fact this is the closest any two planets get all year.

It’s also cool because of the physical reality of what you’re seeing. Venus orbits the Sun closer than Earth, and it’s on the other side of the Sun right now. So you’re looking past the Sun (which is 150 million kilometers away from us) to Venus, which is about 230 million kilometers away. Jupiter is a staggering 950 million kilometers away!

What amazes me is that even though Jupiter is more than four times farther away, it still appears three times bigger than Venus. That’s because Jupiter is ridiculously huge, a dozen times the diameter of Venus.

And one other thing. I’ve written about Juno, the spacecraft currently in orbit around Jupiter. It currently takes 53.5 days to go around Jupiter once and is screaming back toward Jupiter right now. On Saturday, the same day as the conjunction, Juno reaches perijove, its closest approach to Jupiter—just 4,000 kilometers above the cloudtops! After that it heads back out, moving away from the giant planet once again. In October, it’ll fire its engine and lower the orbit, moving it into its science orbit.

My friend Emily Lakdawalla at the Planetary Society has written about Juno many times, and describes an amazing video showing Jupiter as seen from the spacecraft as it moved away from Jupiter nearly two months ago. Here’s the video, but go read Emily’s write-up, because (as usual) it’s great.

I love how Jupiter is half full, a view we don’t get from Earth.

But our view this weekend (and really for several days) of Jupiter will be amazing, and that’s a pretty good consolation prize. I hope you have clear skies and an unrestricted view of this wonderful event.

Correction, Aug. 26, 2016: I originally misstated that the separation was one-fifteenth the width of the Moon, but the Moon is 0.5 degrees (or 30 arcminutes) across. Thirty divided by four is roughly 7.

Aug. 25 2016 9:00 AM

Follow-Up: Just How Hot Was July 2016?

The other day I posted an article about how ridiculously warm July 2016 was globally. Like every month for 10 months in a row, it was the hottest such month since records have been reliably kept (starting in 1880).

This happens so often now that I just repost the same article, with the dates and numbers updated. That’s one way you know the planet’s getting hotter: When every record hot month or year is the month or year you’re in, it’s getting hotter.

But there’s more to this. July is generally the hottest month globally in the year, because it’s summer in the Northern Hemisphere, which has more land mass than the Southern one. Land heats up faster than ocean, so northern summer adds more to the overall warmth. This means July was not only the hottest July on record, but the hottest month on record as well.*

The plot at the top of this article shows that, with July clearly in a class by itself. It also shows that 2016 is hugely favored to be the hottest year globally on record, beating the previous two record holders: 2014 and 2015 (and please read the second paragraph above again if that helps you put this in context).

But it’s worse than that. Records being broken is one thing, but even then you have to look at the trend.

There are various ways to do that, but our brains are keyed to see motion. To that point, here’s an animation of that same graph above, showing each year’s monthly temperatures since records began:

NASA's Global Modeling and Assimilation Office

That animations shows temperature anomalies, the deviation from some average (in this case, the annual average over the date range of 1980 to 2015). As you can see, the yearly graph shifts up and down somewhat randomly until just after the mid-20th century, when the average just starts going up. That’s warming. And this plot downplays the data somewhat, because the average is taken so recently, when global warming already had us in its grasp. Had an earlier average been used (say, 1951–1980, which is a commonly used range) then the scale on the left would show higher numbers.

Deniers downplay all this. They say that it’s been hotter in the past, and that the climate changes all the time. Like so many anti-science claims, that’s a tiny parcel of truth surrounded by a huge dollop of crap. Of course it’s been hotter in the past. Of course climate changes. But the rate of global warming we are seeing now is unprecedented, faster by a huge margin than we’ve seen for more than 10,000 years.

That’s why this is scary. It’s how fast the temperature is climbing. The effects we are seeing now are getting pretty obvious, too. Watch this NASA animation of the Arctic ice melting based on satellite observations, starting from its maximum extent in March 2016 to August (note that the minimum extent won’t be reached until September):

While 2016 is unlikely to set a record low extent of ice, every year for the past decade has been far, far below average. How long will it be before we see an ice-free Arctic summer? A few decades. Not centuries, but decades.

I could go on and on, and believe me I have. It’s stunning that people will still deny the reality of global warming, and ignore the slap-in-the-face effects it’s having on our climate. We know this is happening, and politicians fiddle while the Earth burns.

And as I have also said many times: It’s not too late, and there are things we can do. If you’re a U.S. citizen, where this political problem may be biggest, (politely) let your representatives know you care about this issue, and when November comes, vote.

We all live on this planet, and it’s the only one we’ve got. Let’s end this uncontrolled geoengineering experiment while we still can.

*When I tweeted about it, I meant to say “No human alive today has lived through a hotter July. Ever,” but forgot to add the words “alive today.” A lot of pedants jumped over me about that, when still the meaning was clear in the article. I accept I misphrased it, but it would be kinda nice if people actually clicked a link and read an article before going full denial on the internet. A man can dream.

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