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 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 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!
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!
Why Haven’t Scientists Found ‘Earth 2.0’ Yet?
“Over the past 30 years, astronomers have gone from zero known extra-solar planets to thousands. Periodic changes in a star’s motion or regular brightness dips give them away. Thanks to these techniques, we’ve revealed the masses and radii of worlds nearby and thousands of light years away. Over 200 are Earth-sized, with many residing in the so-called habitable zone around their stars. Yet with everything we’ve found, there are no potentially habitable Earth-like worlds around Sun-like stars.”
One of the greatest success stories over the past 30 years is the giant leap forward we’ve taken in understanding what worlds lie beyond our Solar System. We’ve gone, in that time, from exactly zero known planets beyond our Solar System to thousands. We’ve found worlds far larger than Jupiter, some of which revolve at distances interior to even Mercury’s orbit. We’ve found planets around blue supergiants and red dwarfs. And we’ve discovered small worlds, some of which are even smaller than Earth. Some of them even occur in the so-called habitable zone of their stars.
Yet, despite all of this, we have yet to discover a single Earth-sized world at an Earth-like distance orbiting a Sun-like star. Here’s why we haven’t gotten there yet.
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