Category: earth

This Is Why Earth’s Oceans And Skies Are…

This Is Why Earth’s Oceans And Skies Are Blue

“The sky and ocean aren’t blue because of reflections at all; they’re both blue, but each of their own volition. If you took our oceans away entirely, a human on the surface would still see blue skies, and if you managed to take our skies away (but still somehow gave us liquid water on the surface), our planet would still appear blue.

For the skies, the blue sunlight scatters more easily, and comes to us indirectly from where sunlight strikes the atmosphere as a result. For the oceans, longer-wavelength visible light gets absorbed more easily, so the deeper they go, the darker bluer the remaining light appears. Blue atmospheres may be common for planets, as Uranus and Neptune both possess them, too, but we’re the only one we know of with a blue surface. Perhaps when we find another world with liquid water on its surface, we won’t be so alone in more ways than one!”

The sky is blue. The oceans are blue. Earth, as seen from space, is blue. But have you ever stopped to think about why? Many popular but incorrect explanations abound, such as the idea that sunlight is blue, that oxygen is blue, or that one reflects the other. Of course, none of these are correct! The sky really is blue, and it’s blue because of the physics that governs how light passes through the atmosphere. The ocean is really blue, too; it’s why our planet appears blue from space. But the physics of why the ocean is blue is completely independent of why the skies are blue!

Want to get the real reason why Earth’s oceans and also our skies are blue? Come get the science you crave today.

This Is Why Mars Is Red And Dead While Earth I…

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.

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This Is What Planet Earth’s Ultimate Fat…

This Is What Planet Earth’s Ultimate Fate Will Be

“After ~6 billion years, the Sun will swell, devouring Mercury and Venus, but Earth will persist intact. Our red giant will die after ~9.5 billion years, as Earth continues to orbit the Sun’s white dwarf corpse indefinitely. After 10^15 years, our white dwarf will cool completely, but Earth remains undisturbed. 10^19 years from now, gravitational interactions between galactic masses will likely eject the remnant Solar System.”

There are a lot of different planet-wide catastrophes in store for Earth as time goes on. Regardless of what humans do, however, including when we go extinct, the planet itself will remain. Events like the boiling of our oceans, the Sun becoming a red giant and eventually dying, and even all the stars in the galaxy burning out won’t be enough to destroy our planet. Even the ejection of whatever’s left of our Solar System from our galaxy will leave planet Earth intact. It’s only some 10^25 years from now, based on estimates from orbital mechanics, that our planet will finally meet its destruction.

Come learn about all the destructive events that Earth will face (and survive) in the future, and learn which one will finally do our world in for good!

This Is What Planet Earth’s Ultimate Fat…

This Is What Planet Earth’s Ultimate Fate Will Be

“After ~6 billion years, the Sun will swell, devouring Mercury and Venus, but Earth will persist intact. Our red giant will die after ~9.5 billion years, as Earth continues to orbit the Sun’s white dwarf corpse indefinitely. After 10^15 years, our white dwarf will cool completely, but Earth remains undisturbed. 10^19 years from now, gravitational interactions between galactic masses will likely eject the remnant Solar System.”

There are a lot of different planet-wide catastrophes in store for Earth as time goes on. Regardless of what humans do, however, including when we go extinct, the planet itself will remain. Events like the boiling of our oceans, the Sun becoming a red giant and eventually dying, and even all the stars in the galaxy burning out won’t be enough to destroy our planet. Even the ejection of whatever’s left of our Solar System from our galaxy will leave planet Earth intact. It’s only some 10^25 years from now, based on estimates from orbital mechanics, that our planet will finally meet its destruction.

Come learn about all the destructive events that Earth will face (and survive) in the future, and learn which one will finally do our world in for good!

What Was It Like When Life Began On Earth? “A…

What Was It Like When Life Began On Earth?

“At some point on our planet, in the very early stages, the molecules that are abundant and precursors to life, under the right energy and chemical conditions, began to simultaneously metabolize energy, respond to the environment, grow, adapt, evolve, and reproduce. Even if it would be unrecognizable to us today, that marks the origin of life. In a radically unbroken string of biological success, our planet has been a living world ever since.

While Venus and Mars may have had similar chances, radical changes to Venus’ atmosphere rendered it a searing hothouse world after just 200-300 million years, while the death of the Martian magnetic field caused its atmosphere to be stripped away, rendering it solid and frozen. While asteroid strikes may send Earth-based life off-world, throughout the Solar System and galaxy, all the evidence suggests that we are where it started.

By 9.4 billion years after the Big Bang, Earth was teeming with life. We’ve never looked back.”

When most of us learned about the history of life on Earth in school, all we had were ideas and theories about how it might have gotten started. As you may have guessed, science progresses quickly, and we now have extraordinary evidence for an ancient universal common ancestor, for life existing just a few hundred million years (at the latest) after Earth’s formation, and for life beginning on Earth itself, not before. We even have candidate locations for where!

Come get the up-to-date story on what it was like when life began on Earth. This is your story, too!

The Pale Blue Dot Celebrates Its 29th Annivers…

The Pale Blue Dot Celebrates Its 29th Anniversary, Reminding Us How Small And Fragile We Are

“But the most striking thing about these pictures is what Voyager 1 cannot see. In the single pixel that is Earth, all we can see is its average color and brightness. We cannot see its phase; we cannot see clouds, oceans, or continents; we cannot see our Moon. We cannot see the lights that illuminate our nighttime side. We cannot see our cities, monuments, or any signs of human activity. From 6 billion kilometers away, we are only a dot.

We have not even reached cosmic scales in this image. The Sun is still 8 million times brighter than the next brightest star, with the closest exoplanets approximately 1,000 times more distant than the ones in our Solar System. And still, even at such a close distance, there are no visible signs that anything of interest exists on planet Earth.”

Sometimes, I know, it seems like there is nothing out there that could possibly unite us all. Ideologies, politics, and our visions for the future divide us so thoroughly, that it’s easy to lose sight of what we all have in common: our place in the Universe. 29 years ago, today, an image was released that truly put it all into perspective: the Pale Blue Dot. From a distance of more than 6 billion kilometers, Earth was not even a single pixel, captured amidst the scattered light rays of the Sun. No sign of life, civilization, or even our oceans can be seen. Yet, from three times the distance to Pluto, that one dot contains us all.

Take a little bit of time today to gain a little perspective, and remember the most important lesson of all: in the human enterprise, we’re all in this together.

Earth Is Drifting Away From The Sun, And So Ar…

Earth Is Drifting Away From The Sun, And So Are All The Planets

“The Sun’s mass loss, by burning its nuclear fuel, ensures that every mass orbiting in our Solar System is slowly spiraling outward as time goes on. Some 4.5 billion years ago, our planet was around 50,000 kilometers closer to the Sun than it is today, and will grow more distant more rapidly as the Sun continues to evolve.

With each and every orbit that passes, the planets become progressively less tightly-bound to our Sun. The rate at which the Sun burns through its fuel is increasing, accelerating the rate at which all the planets spiral outwards. While this should never unbind any of the planets we have today, the slow, steady, outward migration of every world is inevitable.

We’re closer to the Sun, this year, than we’ll ever be again. This is true for every planet around every established star in the Universe, too, giving us one more reason to appreciate all that we have today.”

January 3rd, 2019, marks Earth’s perihelion: our point of closest approach to the Sun. Every planet, asteroid, Kuiper belt objects and more has one. But one fact about our perihelion is that, with every year that goes by, our point of closest approach moves out farther and farther from the center of our Solar System. Every year, for Earth, marks another 1.5 centimeters of distance that’s placed between ourselves and the Sun.

How does this happen? Why does this occur? And how come we spiral outwards, instead of inwards? Come learn the science behind perihelion today!

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Earth: Hi sun!

Sun: …

Earth: …

Sun: Dad?

This Is How The Sun Moves In The Sky Throughou…

This Is How The Sun Moves In The Sky Throughout The Year

“It’s easy to see that the topmost point corresponds to the summer solstice, while the lowest point corresponds to the winter solstice, but there is no special astronomical significance to the “crossing-point” in the Sun’s analemma as seen from Earth. Occurring approximately on April 14th and August 30th, those dates are only determined by the way our seasons, determined by axial tilt, align with our planet’s orbit around the Sun.

If our perihelion and aphelion were aligned with the equinoxes, rather than the solstices, we’d have a teardrop-shaped analemma, rather than a figure-8, which is how the Sun appears from Mars! The analemma is the beautiful, natural shape traced out by the Sun over time, creating a figure-8 as both our orbit and axial tilt dictate. Enjoy the Sun’s motion through our skies, as its unique cosmic pirouette is due to our planet’s one-of-a-kind motion through space!”

You might notice that the Sun is changing its position in the sky, while sunset and sunrise times also change. But did you know that you’d get this bizarre, pinched, figure-8-like shape if you took a picture of the Sun every day throughout the year at 24-hour intervals? It’s true! The shape is known as Earth’s analemma, and it’s determined by a variety of factors that you must consider all of in order to get the explanation right. 

Come learn how (and why) the Sun moves the way it does throughout a year as seen by every location on Earth, including yours!