This Is Why Mars Is Red And Dead While Earth Is Blue And Alive
“Both Mars and Earth had early atmospheres that were heavy, massive, and extraordinarily rich in CO2. While Earth’s carbon dioxide got absorbed into the oceans and locked up into carbonate rocks, Mars was unable to do the same, as its oceans were too acidified. The presence of sulfur dioxide led to Martian oceans that were rich in sulfuric acid. This led to geology of Mars we’ve discovered with rovers and landers, and pointed to a different cause — the solar wind — as the culprit in the mystery of the missing Martian atmosphere.
Thanks to NASA’s MAVEN mission, we’ve confirmed that this story is, in fact, the way it happened. Some four billion years ago, the core of Mars became inactive, its magnetic field disappeared, and the solar wind stripped the atmosphere away. With our magnetic field intact, our planet will remain blue and alive for the foreseeable future. But for a smaller world like Mars, its time ran out long ago. At last, we finally know why.”
For most of the 20th century, we knew that Earth had a carbon dioxide-rich past for its atmosphere, but that those atmospheric molecules were deposited into the ocean and precipitated or fossilized out as carbonate rocks like limestone and dolomite. We assumed that Mars, which once had a thick atmosphere and a water-rich surface, lost its atmosphere the same way. But landers and rovers changed all of that, discovering very little in the way of carbonate rocks, meaning that there must have been a different process at play to strip the Martian atmosphere away.
It wasn’t until NASA’s MAVEN mission that we knew for sure! Come learn why Mars is red and dead while Earth is blue and alive today.
5 Reasons Why Astronomy Is Better From The Ground Than In Space
“5.) On Earth, you can observe from anywhere you want. Once your observatory goes to space, gravity and the laws of motion fix, at any given time, exactly where that spacecraft is going to be. Plenty of astronomical curiosities can be seen from everywhere, but there are some spectacular events that require you to be in a very specific location at a particular moment in time. Occultations are an extreme example of this, where a distant, small object in the Solar System passes in front of a background star, but only for a brief instant in a particular location. Neptune’s moon Triton and New Horizons’ first post-Pluto destination, MU69, both occulted background stars, with Triton doing so regularly. Space telescopes have never been lucky enough to catch these, but thanks to mobile observatories like NASA’s SOFIA, we’ve learned how Triton’s atmosphere changes with its seasons, and we’ve even discovered a small moon around MU69! Because we don’t put all our eggs in the telescopes-in-space basket, we can do the unique science that the light arriving at our world enables.”
When it comes to astronomy, space telescopes get all the love. By flying above the atmosphere, there’s no need to wait until the atmospheric and day/night conditions are right to observe; you can look at whatever you want pretty much whenever you want, and for as long as you want. You don’t have to contend with clouds or atmospheric turbulence, and the entire electromagnetic spectrum is available to look at. We normally think of these advantages, but we hardly ever think about how much worse many things are in astronomy from space. But there are legitimately huge advantages to being on the ground, and cost doesn’t even need to be a factor to come up with five tremendous ones!
I resisted the urge to make a “groundbreaking” joke in the article, but the science is unarguable. Come learn the five reasons why astronomy is better from the ground than in space!
Ask Ethan: Why Does Mars Have A Bright, Red Sky?
“We, the physicists, know, that the brightness of the sky is caused by the light of the Sun, which is scattered on the matter of the atmosphere. The brightness of the sky directly corresponds to the mass of matter in the atmosphere. […] But what can we see on the pictures from the Curiosity, Spirit & Opportunity rovers? The incredibly bright sky and incredibly blurred mountains! How can you explain it?”
Before we ever sent a spacecraft to Mars, we knew that its atmosphere was thin and sparse, and that it was made mostly of carbon dioxide gas. We anticipated that the sky, therefore, would appear like a much fainter, thinner, sparser version of our own, mostly transparent atmosphere. But that isn’t how things worked out at all! Instead, the atmosphere on Mars appears bright, reddish, and (depending on conditions) somewhat varied in color. This isn’t due to false coloration issues, as some might think, but rather to the fact that the Martian atmosphere is rife with the same thick, desert-like dust that covers the surface of the planet! In addition, the mountains and geologic features in the distant backgrounds of images from Mars’ surface appear obscured, as though they’re in some kind of fog, and sunsets appear a bizarre blue. Why does this happen?
Believe it or not, the answer is all part of a simple, compelling, and self-consistent picture. (And no, it’s not because they’re color-corrected Earth photos!) Come get the full story on this edition of Ask Ethan!
Sorry, Earth, The Ozone Layer Isn’t Healing Itself After All
“Owing to global warming, there are suggestions that the tropopause has risen and will continue to rise, the troposphere has warmed, and these phenomena may have an effect on ozone concentrations in the lower stratosphere. Furthermore, greenhouse gas-induced climate change appears to be causing an increase in upwelling in the tropics, which could decrease stratospheric ozone there, according to simulations. The exact mechanism responsible for these changes has yet to be identified, but the data is clear: the “100% recovery by 2100” prediction didn’t include these results. With this new understanding, that recovery may be stalled or pushed out to extremely long timescales, and global warming may be exacerbating or even causing this trouble.”
More than 25 years ago, humanity banded together to accept the Montreal Protocol: a promise to eliminate CFCs and stop destroying the ozone layer. As aerosol use changed, things appeared to improve. Our measurements of the ozone in the upper stratosphere, particularly over human-populated areas, was increasing again, and it looked like the ozone layer was recovering. But more recently, we began measuring not only the upper stratosphere, but the ozone density in the lower stratosphere and the troposphere. What we’ve just found is shocking and disappointing: there is no net recovery of ozone in our atmosphere. The decreases in lower stratospheric ozone offset any increases in the other layers, meaning that the ozone layer isn’t recovering, after all. While scientists aren’t sure why, there’s one key ingredient that might be the unexpected culprit: global warming.
There’s more science to be done, but what we’ve learned is vital: the ozone layer won’t be repaired by 2100, and unless we figure out what’s going on, we might not be able to instill a recovery at all.
Do Earth-Sized Planets Around Other Stars Have Atmospheres? James Webb Will Find Out!
“Even so, because of its ability to measure light to high sensitivity far into the infrared, there’s a remarkable hope for determining whether these worlds have atmosphere regardless of any other measurements. As planets orbit their star, we see different phases: a full phase when it’s on the far side of the star; a new phase when it’s on the near side, and everything in between. Based on the temperature of the world at night, we’ll receive different amounts of infrared light from the "dark” side that faces away from the Sun. Even without a transit, James Webb should be able to measure this.“
The overwhelming majority of Earth-sized, potentially habitable planets that Kepler found are in orbit around red dwarf stars. In many ways, this is great: red dwarf stars are stable, temperature-wise, for longer than our Sun. Their planets are easier to detect, and they will be the first Earth-sized ones we can measure the atmospheres of directly. But even if we can’t make those measurements with James Webb, we’ll be able to learn whether they have atmospheres or not via a different method: by measuring the infrared radiation coming from the planets themselves in various phases. Just as we can measure the presence of Venus’ atmosphere from the hot, infrared radiation emanating from it even on the night side, we can make those same measurements with James Webb of other Solar Systems. By time the early 2020s roll around, we’ll have our first answers to this longstanding debate.
Many scientists think that Earth-sized planets around M-class stars will have no atmospheres left; others think there’s a chance they survive. Here’s how James Webb will find out!
The Hubble Space Telescope Is Falling
“The truth is that, more than any other observatory in history, the Hubble Space Telescope has changed how we view the Universe. Although other ground-based and space-based observatories have been built and will be flying that surpass Hubble on a number of fronts, for some classes of observing, it’s still the best tool humanity has ever created. But by the very nature of its orbit, not only is its lifetime finite, but its demise will come in a horrific, potentially dangerous fashion if we do nothing. Saving it for further use is a long-term project that requires planning now. Hubble is falling, and if we don’t take the steps to catch it soon, it will be too late.”
Orbiting at hundreds of miles above Earth’s atmosphere, you’d think the Hubble Space Telescope would be safe and stable for a long time. But despite our definitions, Earth’s atmosphere doesn’t “end” and space doesn’t “begin” when we get 60 miles (100 kilometers) up. Instead, Earth’s atmosphere continues, albeit tenuously, for incredible distances, until it eventually merges with the solar wind. It’s the fourth (of five) layers that contains the Hubble Space Telescope: the thermosphere. Although each oxygen molecule might travel for a kilometer before striking another, the presence of these molecules is enough to slowly produce a drag on Hubble. Over the timespan of years and decades, it loses altitude and begins to fall. If we do nothing, then by the late 2020s to the mid-2030s, it will uncontrollably de-orbit on its own. Our greatest optical observatory will be lost, and there are no plans to save it.
Come learn how the Hubble Space Telescope is falling, what we can do, and why we need to act now.
How Much CO2 Does A Single Volcano Emit?
“The Earth’s mantle is full of trillions of tons of carbon alone, and if even a small percent of it were added to the atmosphere, it has the potential to be absolutely catastrophic for the planet. But given the scales of the eruptions we actually have, less than a billion tons are emitted per year thanks to volcanic activity: a small enough amount that our planet can sequester roughly the same amount on a per-year basis. If not for the influence of humans, the climate and carbon dioxide concentrations would be stable. Rising CO2 is a problem that we’re actively causing, and if we want to fix it, that’s up to us, too.”
Every year, dozens of volcanoes actively erupt across the Earth’s surface. In addition, other active volcanoes continue to release greenhouse gases into the atmosphere, and even dormant volcanoes and other fissures in the Earth contribute to our overall carbon dioxide content. If we want to understand the effects that humanity is having on our atmosphere, we need to understand the natural contribution first. Tremendous advances in measuring these natural contributions have occurred since the 1990s, as we’ve now quantified to a much-improved precision the effects of these natural components. Volcanoes of all types, on average, emit somewhere in the ballpark of 645 million tons of CO2 per year, with occasional large eruptions adding tens or possibly even a hundred million tons to that total.
But that’s barely 2% of what humanity emits in a given year. Come find out the science of volcanic CO2, and put humanity’s contributions into its valid scientific perspective.
There’s No Science Behind Denying Climate Change
“Indeed, if there were a conspiracy, if climate science were a hoax, and if all this research were incorrect, all it would take was one scrupulous, competent scientist. But every scrupulous, competent scientist that investigates it has come to the same conclusion: it’s real, it’s warming, and it’s our CO2 that’s doing it. You are free to deny climate change if you want, but there’s no scientific leg to stand on if you do.”
It only makes sense that scientists should debate and argue over the findings in their field. Given all the suites of data available that are relevant to a particular physical phenomenon, how do we put it together in a way that is scientifically robust, allow us to understand and predict what’s happening, and justifiably attribute the causes of observed phenomena? It’s a daunting task, and one that you need science for. So when it comes to global warming, why aren’t the arguments about the temperature and atmospheric concentrations of gases over time? Why are they instead about scientific personalities, profitability, conspiracies and hacked emails? Why, instead, aren’t those opposing the science of human-caused climate change pointing to data and scientific arguments?
After all, the only thing it would take to overturn anthropogenic climate change was one compelling scientific argument. Learn why, if you value scientific thinking, it’s incompatible with climate change denial.