Profile cover photo
Profile photo
Ethan Siegel
Science writer, professor and theoretical astrophysicist
Science writer, professor and theoretical astrophysicist

Ethan's interests
View all
Ethan's posts

Post has attachment
“But the “point effect” is more subtle. When there’s an electric field gradient, charges pool at the edge of a conductor. At a point, the charges reach a higher density than under any other conditions. More than perhaps two inches (5 cm) away from the tip of such a rod, the electric field around the top of the building becomes more dissipated. As a result, if there are many tall buildings around with lightning rods on them, lightning will be more likely to strike the ones without a pointed tip. The rod itself is more protection for a building if it does get struck by lightning, but the tip makes it less likely the building will be struck if there’s a better source around.”

You’ll often hear charges that science has become too politicized, but it’s the other way around. Science is our best way of drawing conclusions about the natural world, including how natural and human-caused phenomena work and interact together. When politics, biases, agendas or predispositions get in the way, however, they can derail actual knowledge and cause us to live in an inferior fashion. This isn’t new to modern times, but goes back at least hundreds of years, to Ben Franklin. Franklin, who invented the lightning rod, came up with the design that would save countless buildings from fire once that rod was applied. Yet the inability of many dogmatic people – including King George III of England – to accept the reality of the science led to a huge number of disasters and fires, many of which revisionist historians still try and cover up today.

The science doesn’t lie, and the safety and efficacy of modern, properly-implemented lightning rods is proof of that. But the story of how science was politicized way back in the 1700s is something we can all learn from.

Post has attachment
“Unlike the worlds in our Solar System, each one should be tidally locked to the parent star, meaning that the same side always sees “day” while the opposite side resides in eternal night. Yet life on Earth began in the oceans, and of these seven worlds, the fourth, fifth and sixth might all have conditions to support liquid oceans or lakes – if the atmosphere is favorable – bathed in eternal sunlight.”

What is it that makes our Solar System special? It’s Earth, of course. A rocky planet of the right mass and composition, the right distance from our Sun, the right atmosphere, the surface oceans, and all the life that’s ensued is what makes us special. Not just special, but unique, at least among the planets we’ve found so far. But there are other planetary systems out there with Earth-like worlds. Similar to Earth in mass, size, temperature and many other conditions, these might represent planets where life similar to what we find here arose. For the first time, we’ve found a planetary system with not just one Earth-like, potentially habitable world, but three!

Come meet the worlds around the ultra-cool star TRAPPIST-1, and learn what the prospects are for these worlds being truly Earth-like.

Post has attachment
“While the large Moon will be destined to be tidally destroyed and drawn to the surface through friction with Mars’ atmosphere, the other two moons could remain. Phobos and Deimos had a much larger sibling at some point in the past, but it may have lasted only for a few million years. After billions of years more, these two small moons remain. Perhaps in a few billion more, Phobos may be destroyed as well. If the new theory is right, a future scientist will only have Deimos and the basins on Mars to piece together this story from. It’s a stark reminder that in the Solar System and the Universe in general, the past is gone. All we have left to base its history on are the survivors.”

Compared to the other moons we know of in the Solar System, Mars’s two, Phobos and Deimos, are incredibly difficult to explain. They look like captured asteroids, being small, irregular, and exhibiting the right surface features. But captured asteroids form inclined or even retrograde orbits quite distant from their planet, while Phobos and Deimos live in circular, equatorial, close-in orbits to Mars. An alternative theory to the captured asteroid scenario is that the moons of Mars formed from a giant impact that kicked up a circumplanetary debris disk, similar to how Earth’s moon formed. But those scenarios never lead to merely two small moons; there’s always at least one large one. Thanks to a new simulation, all the pieces might finally be coming together.

Could Mars have had an inner, larger moon in the past that’s now decayed and collided back with the red planet? Get the story today!

Post has attachment
“When the ground’s brightness surpasses the sky’s, clouds appear bright against the night, rather than as dark silhouettes. While cameras reveal many more stars than the unaided eye can, a dark, night sky offers spectacular views to humanity. As urbanization increases, dark skies become rarer and less pristine.”

For all of human history, we’ve battled against the limitations of our bodies and the natural world. That’s led to the development of artificial lighting: from fire to modern electric and LED lights. Despite being able to see our surroundings much more clearly at all hours regardless of the Moon or the clouds, we’ve also lost something spectacular: the night skies themselves. There are thousands of stars visible to the naked eye from a truly dark-sky location, yet such places are increasingly harder to come by. East of the Mississippi in the United States, they barely exist at all. From many urban locations, even bright, easily recognizable sights like the North Star or the Big Dipper are no longer visible.

Come see what light pollution costs us every night, and learn why, if we don’t do something, the only place to get dark skies will be in space.

Post has attachment
"You’d need to strip off the H/He envelope early, and most of the rest of a “puffy” atmosphere as well. You’d need to strip the world down to only a thin atmosphere, but not beyond that. And then you’d need to have a planetary migration outwards occur, away from the star and out towards a more temperate zone. Certainly, this is possible, and pointing to the possibility of planetary migration in our own Solar System is a good example. You’d also want a star that was G-class or more massive, for the ultraviolet radiation providing a necessary “kick” to the atmospheric particles, but not too much more massive so that the lifetime of the star/planetary system was too short."

How can you make a super-Earth habitable? How does the Universe become reionized? How will James Webb tell us what we don't yet know, and how can we go beyond the first stars? How do the Big Bang and the expanding Universe work? And most importantly, how do we get correct information to people (and protect them from misinformation) in today's world?

Lots of answers, lots of questions and some things we can all think about on this edition of our Comments of the Week!

Post has attachment
“Sometimes (usually Fridays after work) my friend Scotty beams me up to USS Enterprise for a ride around Sun following the orbit of planet Earth. The warp takes about 2 hours, so I guess our speed is very close to light speed, but not quite. During the ride I usually have a couple of beers, so when Scotty beams be back to my front door, my wife has difficulties believing me when I tell her that I was not at the local Pub…”

So, your friend on the USS Enterprise beamed you aboard, took you on a relativistic journey at impulse speeds around the Solar System, and brought you back to your starting point. You find that less time has passed for you than your family who remained on Earth, yet you’ve traveled a much greater distance. How does this all work? How much energy does it take, what’s the science behind it, and how do you get your family to believe you when you tell them what happened to you? Some basic advice: give them times in their reference frame, admit to the drinking you actually do, and if you go someplace unbelievable, take a photo!

To find out even more, and learn about my upcoming new book, Treknology: The Science of Star Trek from Tricorders to Warp Drive, check out this week’s Ask Ethan!

Post has attachment
I wrote a book! It's called Treknology, and it's about the real-life science, up-to-date, about a huge slew of the technologies dreamed up by Star Trek. From warp drive to transporters to VISORs to human life extension to androids and more, you won't want to miss it.

Plus we've got the official license rights from CBS and Paramount, so images from your favorite Star Trek moments will be featured.

The book comes out October 15th, and this is the official announcement from Star Trek!

Post has attachment
“But there’s one killer move that stars have that makes carbon a loser in the cosmic equation: when a star is massive enough to initiate carbon fusion – a requirement for generating a type II supernova – the process that turns carbon into oxygen goes almost to full completion, creating significantly more oxygen than carbon by time the star is ready to explode.”

When the Universe was first born, all we had was hydrogen and helium, with a trace amount of lithium and absolutely nothing else. 13.8 billion years later, hydrogen is still #1 in the Universe and helium is still #2, but lithium isn’t close to #3 anymore: more than two dozen elements have passed it. The key? Stars! Over billions of years, nuclear fusion in the cores of stars have built up all the naturally occurring elements we know of in the periodic table. You might think that since three heliums can fuse together to make carbon, that would be the third most common element in the Universe. And it’s close: carbon comes in at #4. But another element has it beat.

Hydrogen's one, helium's two. Who's number three? This story's for you!

Post has attachment
“ What they find is that the transition from “rocky” world to “gaseous” world occurs at just twice the Earth’s mass. If you’re more that twice the mass of Earth and you receive the same amount of energy from your star, you’ll be able to hold onto a substantial hydrogen-and-helium envelope of gas, creating an atmospheric pressure that’s hundreds or even thousands of times as great as what we have on Earth’s surface. The hope that Super-Earth worlds would be Earth-like is shattered, and we can safely put Super-Earths, Mini-Neptunes and Neptune-like worlds into the same overall category. ”

It was quite a surprise when we started discovering all the exoplanets that were out there. While there’s a big gap between a world like Earth and a world like Uranus or Neptune in our Solar System – 17 times the mass and 4 times the radius – most of the worlds out there fall in between these two types. Super-Earths and Mini-Neptunes are the most common. But it turns out that what we’re calling a “Super-Earth” is a total misnomer! These worlds may be larger than Earth, but they’re much more like Uranus or Neptune than they are like our own. They have big gas envelopes surrounding them, and can even hold on to their young hydrogen and helium. The only way out is to boil the atmosphere away, and if you do, you’ve got a rocky core that’s close enough to its star to be roasted.

Come find out the full story behind why there’s no such thing as a habitable Super-Earth!

Post has attachment
"Would you fire a gun into the air in celebration if you knew that, when the bullet comes down, it could kill somebody? It's no surprise that bullets fired towards a target can easily destroy whatever they run into: a bullet from an AK-47 leaves the rifle traveling at over 1,500 miles per hour (670 meters per second): about double the speed of sound. Despite only having a mass of about five grams -- under a fifth of an ounce -- it's got the energy of a brick dropped from a 30 story building."

Bullets are incredibly dangerous when fired from a gun, but that's true even when they're fired up in the air, not at a target directly. Falling, stray bullets can still reach very large speeds, large enough to break the skin and cause internal damage, potentially even killing someone. There are huge variations in what can happen depending on the weight and size of the bullet, the angle it was fired at, your altitude, the thickness and elasticity of the skin it strikes and where it impacts you. The most dangerous times are New Years and 4th of July in urban areas, and there are numerous documented cases of injury and death resulting.

Don't be an innocent bystander, and don't be part of the problem. There are steps we can all take to be safe, so spread the word!
Wait while more posts are being loaded