Category: earth

Astronomers Debate: How Many Habitable Planets Does Each Sun-Like Star Have?

“We know that there are between 200 billion and 400 billion stars in the Milky Way galaxy. About 20% of those stars are Sun-like, for about 40-to-80 billion Sun-like stars in our galaxy. There are very likely billions of Earth-sized worlds orbiting those stars with the potential for the right conditions to have liquid water on their surfaces and being otherwise Earth-like, but whether that’s 1 or 2 billion or 50 or 100 billion is still unknown. Future planet-finding and exploring missions will need better answers than we presently have today, and that’s all the more reason to keep looking with every tool in our arsenal.”

Most of the time, in science, the quality of our data drives the size of our uncertainties. When we have very little data and it’s only of poor quality, our uncertainties tend to be large; when we have lots of very good data, our uncertainties shrink. NASA’s Kepler mission has provided astronomers with an unprecedented suite of data on exoplanets, revealing thousands of new worlds beyond our Solar System. And yet, despite all it’s found, if you ask the simple question of “how many Earth-like planets orbit a typical Sun-like star,” answers disagree by a factor of 100: from about 1% of stars have them to there’s between 1 and 2 for each and every such star.

What’s the real story? Where do these uncertainties arise, and are they larger than they need to be? Come get the full story (and watch David Kipping’s video at the end) and find out!

This Is Why We Don’t Shoot Earth’s Garbage Into The Sun

“Considering that the United States alone is storing about 60,000 tons of high-level nuclear waste, it would take approximately 8,600 Soyuz rockets to remove this waste from the Earth. Even if we could reduce the launch failure rate to an unprecedented 0.1%, it would cost approximately a trillion dollars and, with an estimated 9 launch failures to look forward to, would lead to over 60,000 pounds of hazardous waste being randomly redistributed across the Earth.

Unless we’re willing to pay an unprecedented cost and accept the near-certainty of catastrophic environmental pollution, we have to leave the idea of shooting our garbage into the Sun to the realm of science fiction and future hopeful technologies like space elevators. It’s undeniable that we’ve made quite the mess on planet Earth. Now, it’s up to us to figure out our own way out of it.”

As human beings continue to lead the technologically advanced lives we’re presently leading, we’re also producing waste of many different types. Biohazards, dangerous chemicals, nuclear waste and other pollutants must be kept out of drinking water, agricultural regions, the oceans, atmosphere, and away from populated areas. You might wonder why, now that we’re well into the space age, we haven’t considered shooting Earth’s most difficult-to-deal-with garbage into the Sun?

Well, we have considered it, and there are good reasons not to do it. If you’ve ever wondered why, you’ll really enjoy this read.

Ten Solstice Facts That Everyone Should Know

9.) The solstices are neither the hottest nor coldest days of the year. This one is actually very specific to Earth: the hottest times of the year typically correspond to approximately 6 weeks after the summer solstice, and approximately 6 weeks after the winter solstice. Other planets don’t have this same phenomenon for one very important reason: they don’t have the majority of their surfaces covered in liquid water.

The oceans themselves, being composed of large quantities of water and containing approximately 1,000 times the mass of Earth’s atmospheres, contain a tremendous amount of heat, and are slow to change their temperatures. We might receive more (or less) energy from the Sun on the summer (or winter) solstices, but the oceans require time to heat up or cool down. Global average temperature extremes, therefore, usually occur in early August and February, rather than at the June and December solstices.”

The solstice, Latin for the Sun standing still in the sky, occurs whenever the Earth’s axial tilt reaches a maximum relative to the Earth’s orbital plane around the Sun. With a tilt of 23.5 degrees, but a tilt that’s independent of our elliptical orbit around the Sun, many surprising and counterintuitive facts arise.

Want to know as many of them as possible? Come get this remarkable and fascinating list of educational facts on this year’s solstice: June 21, 2019!

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 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.

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 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?

“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.