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[NEWS] Some more links about Proxima Centauri b

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The European Southern Observatory provided this artist’s impression of the surface of Proxima b. “The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.”

Like.

Proxima Centauri b has continued to excite over the weekend. The MacLean’s article “Why everyone is excited about an exoplanet named Proxima b”, by Amanda Shendrake, points out the apparent import for a layman’s audience.

Just because an exoplanet is in a star’s habitable zone, however, does not mean it can host life. It simply means that if the exoplanet featured a similar atmosphere and surface pressure as the Earth, the planet could sustain liquid water. Unfortunately, we know nothing about Proxima b’s atmosphere.

For an exoplanet to be potentially habitable, scientists consider more than just whether or not it can host water. The star around which the exoplanet orbits needs to be of a particular type—one that burns long enough to allow life a chance to evolve, and emits appropriate amounts of ultraviolet radiation.

Additionally, the exoplanet must have significant similarities to Earth. The Earth Similarity Index (ESI) is a way to measure this likeness, and it places objects on a scale of zero to one, where one is Earth itself. The closer to 1.0, the more similar the exoplanet is to our home. The measurement takes into account radius, density, escape velocity, and surface temperature.

No other planets in our solar system are Earth-like; however, in addition to being the nearest of the 44 potentially habitable exoplanets we’ve found, Proxima b also has the highest ESI.

(Nice infographics, too.)

At Scientific American, Elizabeth Tasker’s blog post “Yes, We’ve Discovered a Planet Orbiting the Nearest Star but…” notes the many, many caveats around identifying Proxima Centauri b as Earth-like. Sarah Scoles’ Wired article “Y’all Need to Chill About Proxima Centauri b” explores the same territory, and makes an argument as to the underlying motivation for this identification of worlds as potentially Earth-like.

[I]t’s not an Earth twin, no matter what the headlines say, and neither are any other planets scientists have found. Hot Jupiters may be cool; planets that rain glass may be a hit at parties; “Super-Earth” may be fun to say. And getting the full census of exoplanets is valuable. But most scientists, Messeri has found, really just want to find another Earth. Research priorities reflect that. The Kepler Space Telescope, which has discovered more planets than any other enterprise, was “specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone,” according to NASA.

The search for an “Earth Twin” is the quest for a platonic ideal, says Messeri. “It allows us to imagine Earth at its best, Earth as we want to imagine it, Earth that isn’t hampered by climate change or war or disease,” she says.

In other words, Earth as we’ve never known it and never will. If scientists found a twin planet, Pure Earth would become, in our minds, a real place that still exists, somewhere out there.

But we haven’t discovered that place. And we might not ever. On a quest for the perfect partner, you usually find someone who’s pretty cool but yells at you when they’re hungry, or hates your mom. After you sign on to the perfect job, you discover that you’re supposed to wash everyone’s coffee mugs. In that way, finding Proxima Centauri b while searching for Pure Earth is just like every human quest for perfection.

“What we’ve actually found is something more real,” says Messeri, “and less ideal.”

Joseph Dussault at the Christian Science Monitor notes in “Do we need to change the way we talk about potentially habitable planets?” that the language used to describe these worlds may need to be altered, for lay audiences at least. Universe Today’s Matt Williams notes that Earth-like means something that is not a duplicate of Tahiti.

[F]inding a planet that is greater in size and mass than Earth, but significantly less than that of a gas giant, does not mean it is terrestrial. In fact, some scientists have recommended that the term “mini-Neptune” be used to describe planets that are more massive than Earth, but not necessarily composed of silicate minerals and metals.

And estimates of size and mass are not exactly metrics for determining whether or not a planet is “habitable”. This term is especially sticky when it comes to exoplanets. When scientists attach this word to extra-solar planets like Proxima b, Gliese 667 Cc, Kepler-452b, they are generally referring to the fact that the planet exists within its parent star’s “habitable zone” (aka. Goldilocks zone).

This term describes the region around a star where a planet will experience average surface temperatures that allow for liquid water to exist on its surface. For those planets that orbit too close to their star, they will experience intense heat that transforms surface waster into hydrogen and oxygen – the former escaping into space, the latter combining with carbon to form CO².

This is what scientists believe happened to Venus, where thick clouds of CO² and water vapor triggered a runaway greenhouse effect. This turned Venus from a world that once had oceans into the hellish environment we know today, where temperatures are hot enough to melt lead, atmospheric density if off the charts, and sulfuric acid rains from its thick clouds.

For planets that orbit beyond a star’s habitable zone, water ice will become frozen solid, and the only liquid water will likely be found in underground reservoirs (this is the case on Mars). As such, finding planets that are just right in terms of average surface temperature is intrinsic to the “low-hanging fruit” approach of searching for life in our Universe.

Even so, the optimism expressed by Bloomberg View’s Faye Flam in “What the New Planet Says About Life in the Universe” is something I would like to cling to. Proxima b’s ideal, or at least worlds like this ideal, might be perfectly suited for life.

Studying this planet could reveal something important about the timeline of life in the universe, and whether we earthlings are early to the party. That’s because stars like Proxima Centauri are the future of the universe. Called red dwarfs, these make up the majority of stars in the galaxy, and they live about 1,000 times as long as our sun.

In a paper made public last month, Harvard astronomer Avi Loeb looked at the cosmic implications of life surrounding red dwarfs. Loeb calculated that if life is just as likely to form around these stars as sun-like ones, then the vast majority of life in the universe has yet to be born, and we earthlings are not just early, he said, but “premature.”

That’s because scientists believe eventually, all the raw materials for star formation will be used up and all the stars will die, leaving a dark universe of dust and black holes. For most of the trillions of years stretching between now and cosmic darkness, red dwarfs will be the only game in town.

The papers at arXiV at least allow for hope. Why not encourage it?

Written by Randy McDonald

August 28, 2016 at 10:29 pm

[ISL] “Last mammoths on Alaska island likely died of thirst”

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CBC reported on the grim findings of the researchers who determined why the mammoths of Alaska’s Saint Paul Island, last of their kind, died out.

St. Paul Island’s mammoths were a vulnerable population that probably never numbered more than 30, [one researcher] estimates. Pinpointing the cause of their extinction “just sort of underscores the precariousness of small island populations to what seems like fairly subtle environmental change.”

Even today, the crater lake that the researchers studied is only a metre deep. The researchers drilled through the ice in winter, into the layers of sediment deposited on the bottom of the lake over thousands of years.

There they found mammoth DNA, spores of fungi that can only live in the fresh dung of large mammals like mammoths, and the remains of aquatic insects that contain chemical information about water levels over the lake’s history.

Together, the data pinpoint the time of extinction at 5,600 years ago — about 900 years after the date of the youngest mammoth remains ever dug up on the island — and chronicle the deterioration of the lake during the last days of the mammoths.

The result doesn’t just solve a longstanding mystery about a puzzling extinction.

It may also be a warning about the seriousness of a problem that has never been linked to extinctions in the past, but is relevant for human communities in our own age of rapid climate change, rising seas and a coastal flooding[.]

Written by Randy McDonald

August 28, 2016 at 7:15 pm

[BLOG] Some Wednesday links

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  • Dead Things looks at the health issues of a hadrosaur.
  • The Dragon’s Gaze notes close binary systems may not support planets very well.
  • Joe. My. God. notes Trump’s reaction to Obama’s statement that he was unfit.
  • The Map Room Blog notes Russia’s issues with Google over the non-recognition of Crimea’s annexation.
  • Marginal Revolution notes that driverless taxis are coming to Singapore.
  • The Power and the Money’s Noel Maurer disproves arguments claiming that Pennsylvania is uniquely suited for Trump.
  • Peter Rukavina shares his schedule for the Island Fringe.
  • Spacing Toronto notes the problem of distracted cycling.
  • Window on Eurasia looks at language death in the North Caucasus.

[BLOG] Some science links

  • blogTO looks back on a Toronto heat wave in 1935.
  • Centauri Dreams looks at the K2-72 and Kepler-80 systems.
  • D-Brief reports on early signs of global warming in Siberia and looks at how African honeyguide birds work together with human hunters.
  • The Dragon’s Gaze looks at the search for habitable planets around red dwarfs, looks at the habitability of planets with eccentric orbits, and notes that warm Jupiters can co-exist with smaller planets nearby.
  • The Dragon’s Tales look at a proposed Europa mission, and notes an astrobiological model of Titan’s atmosphere.
  • Imageo shares Juno’s first view of Jupiter.
  • The Planetary Society Blog reports about the Planetary Society’s presence at San Diego Comic-Con.

[NEWS] Some Thursday links

  • Bloomberg notes concern in Northern Ireland’s border towns over Brexit, reports that Morgan may shift its offices from London to Dublin or Frankfurt, and looks at the hostile reaction Donald Trump is likely to receive in Scotland.
  • Bloomberg View looks at the vexed issues of American funding for Israel’s defense industry.
  • The CBC notes the discovery of a transmissible cancer affecting shellfish.
  • MacLean’s takes a sanguine view of millennials in Canada who stay with their parents.
  • The National Post interviews a Muslim woman attacked in London, Ontario, and notes odd institutional issues raised against the Pride parade in Steinbach.
  • The New Republic looks at the impact the collapse of Barnes & Noble would have on American publishing and literature.
  • Open Democracy fears the effect of Brexit on central and eastern Europe.
  • Transitions Online notes the lack of reciprocation for Bulgarian Russophilia.
  • Wired notes that the Brexit referendum is a major inflection point in the European Union’s history.

[BLOG] Some Tuesday links

  • blogTO notes the spotting of a High Park capybara.
  • Centauri Dreams reflects on the Pluto landscape.
  • The Dragon’s Gaze links to a paper looking at percolation theory in connection to the Fermi paradox.
  • Joe. My. God. notes the homophobic and useless reactions of one anti-gay group to HIV.

  • Language Hat links to an essay linking language with emotion.
  • The NYRB Daily points to a 13th century anti-Semitic caricature.
  • Towleroad examines George Michael as a gay icon.
  • The Volokh Conspiracy talks from a libertarian perspective about the negative consequences of a Trump administration for freedom.
  • Window on Eurasia suggests Ukraine should exit the Minsk process as harmful to its interests.

[NEWS] Some Monday links

  • Bloomberg notes concern in Asia regarding Brexit, and reports on a Taiwanese call to China to heal from Tiananmen.
  • CBC notes a shocking proposal to assemble a human being using an artificial genome.
  • io9 notes the interest of the Chinese government in setting up a local science fiction award.
  • MacLean’s notes Russian crime gangs are blackmailing gay men.
  • The National Post observes one suggestion that Stonehenge was originally Welsh, and reports on a Wildrose parliamentarian in Alberta who compared a carbon tax to the Ukrainian genocide.
  • Open Democracy examines English identity in the context of Brexit and reports on South America’s Operation Condor.
  • The Toronto Star reports on an African grey parrot that may be a murder witness and notes Trudeau’s statement that preserving indigenous languages is key to preventing youth suicides.
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