Scientists at the Nordic Optical Telescope didn't discover 55 Cancri e: but they're the first to observe the super-Earth from Earth's surface. The planet is too hot for life: but 55 Cancri f is another matter. I'll get back to that.
Other scientists are fine-tuning how we can search for life in the universe.
- Kepler Rides Again
- Planet-Spotting: Nordic Optical Telescope's 'First'
- 'Mirage Earths:' Life and Low-Mass Stars
(From PlanetQuest, NASA/Jet Propulsion Laboratory; via Wikimedia Commons; used w/o permission.)
We've found nearly two thousand planets so far, mostly in our sun's neighborhood. It's a small sampling of the Milky Way galaxy: but big enough to estimate what we'll find.
On average, it looks like each star has at least one planet: and about one in five stars like ours have an Earth-sized planet in the habitable zone. Our galaxy has at least 200,000,000,000 stars: so eventually we should find tens to hundreds of billions of planets.
Life may exist on many of them: or we may be standing on the only planet that supports life. Like I've said before, right now we don't know.
It's like the situation, not quite eight centuries back, when some European scholars said other worlds might exist. Many of their colleagues were ardent fans of Aristotle: and said other worlds can't exist, because Aristotle said so.
Eventually, Catholic Church stepped in: and ever since 1277, claiming that we have to be standing on the only world has been against the rules. Basically: God's God, Aristotle's not. (June 27, 2014; February 23, 2014)
I think the same principle applies to whether or not there's life in the universe. I'm not going to try telling God what the Almighty can or cannot do.
"Then God said, "Let there be a dome in the middle of the waters, to separate one body of water from the other." And so it happened:Someone I knew said that our sun orbits Earth, because that's what Joshua 10:13 says, but I have yet to meet someone who insists that we live under a big dome.
"God made the dome, and it separated the water above the dome from the water below it.
"God called the dome 'the sky.' Evening came, and morning followed - the second day."
The "dome in the middle of the waters" echoes Mesopotamian beliefs about the world. We've learned quite a bit since then. (July 15, 2014)
Genesis wasn't written by a literal-minded contemporary American. The two creation stories say that God created a good, ordered, world: but didn't give us nitpicking details that we've been learning on our own.
There's more to reality than what science can verify: but science, studying this universe, is part of being human. Science is one of the Holy Spirit's seven gifts: knowledge. (Catechism, 279-308, 1831, 2293, 2727)
Bottom line? Poetry isn't science, and that's okay. (July 18, 2014)
"When I see your heavens, the work of your fingers, the moon and stars that you set in place -Knowing that the universe is billions, not thousands, of years old; and that Earth isn't flat; invites "...even greater admiration for the greatness of the Creator...."
"4 What are humans that you are mindful of them, mere mortals that you care for them?
"5 Yet you have made them little less than a god, crowned them with glory and honor."
"How precious to me are your designs, O God; how vast the sum of them!
"Were I to count, they would outnumber the sands; to finish, I would need eternity."
I believe God made the things of this world and the things of faith, so honest study of the universe can't interfere with faith. (Catechism, 159, 214-217, 283)
As Leo XIII wrote, "truth cannot contradict truth." ("Providentissimus Deus," Leo XIII (November 18, 1893))
You probably remember the Hertzsprung–Russell diagram from science textbooks: with bright, hot stars in the upper left corner and dim, cool stars in the lower right.
In the last hundred or so years, scientists have learned how stellar evolution works: how stars form and change.
The more massive a main sequence star is, the brighter it is.
Massive stars like Theta1 Orionis C have an enormous habitable zone, but it's not likely we'd find life on planets of high-mass stars. They don't last long enough.
Theta1 Orionis C is about 1,200,000 years old now. At this point in the Solar System's history, Earth's surface was still partly molten: thanks to volcanic activity and frequent meteor and asteroid strikes.
We're pretty sure that the earliest known life on Earth showed up a few hundred million years after our planet formed.
Let's say that a hypothetical Earth-double orbiting Theta1 Orionis C's cooled down really fast, and microorganisms are living there now. A few million years from now, scientists expect the star to swell into a red supergiant before exploding as a supernova.
That doesn't give the microcritters much time to develop.
Epsilon Tauri is the most massive star I've read about with a known planet. It isn't a particularly big star. It's only 2.7 times as massive as our sun, and was probably a blue-white class A star like Vega when it was on the main sequence, and I'm wandering off-topic.
Low-mass stars have tiny habitable zones, the region where liquid water could exist on a planet with a significant atmosphere.
But because they're the most common sort of star, some scientists think we've got the best chance of finding life on one of their planets. (October 18, 2013; May 10, 2013; February 8, 2013)
These stars burn through their hydrogen very slowly. As a Wikipedia page said, because the universe is so comparatively young, no red dwarfs have run out of fuel yet.
More than you may want to know about:
- Stars and planets
- Planets and life
- Habitability of red dwarf systems
- How did the solar system form?
Natural History Museum, London
- List of multiplanetary systems
(Information about the 715 exoplanets discovered in February 2014 is outdated as of December 17, 2014)
- Natural satellite habitability
- Origin of water on Earth
- Planetary system
- Habitability of red dwarf systems
(From NASA Ames/W. Stenzel, used w/o permission.)
(If positioned correctly, pressure from sunlight will balance the spacecraft, holding it steady for observing sessions. (See full-size illustration at "Kepler's Second Light: How K2 Will Work.))
"NASA's Kepler Reborn, Makes First Exoplanet Find of New Mission"I wrote about Kepler's new mission in May. Mission planners had the Kepler spacecraft fold its solar panels into something like a mansard roof, so they could act as a solar sail. That gave the robot observatory good-enough attitude control for its new mission. Just as important, they wangled funding for the K2 mission. (May 30, 2014)
(December 18, 2014)
"NASA's planet-hunting Kepler spacecraft makes a comeback with the discovery of the first exoplanet found using its new mission -- K2.
".The discovery was made when astronomers and engineers devised an ingenious way to repurpose Kepler for the K2 mission and continue its search of the cosmos for other worlds....
"...Lead researcher Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, studied publicly available data collected by the spacecraft during a test of K2 in February 2014. The discovery was confirmed with measurements taken by the HARPS-North spectrograph of the Telescopio Nazionale Galileo in the Canary Islands, which captured the wobble of the star caused by the planet’s gravitational tug as it orbits.
"The newly confirmed planet, HIP 116454b, is 2.5 times the diameter of Earth and follows a close, nine-day orbit around a star that is smaller and cooler than our sun, making the planet too hot for life as we know it. HIP 116454b and its star are 180 light-years from Earth, toward the constellation Pisces...."
The NASA press release talked quite a bit about what they hope K2 will do: but not much about HIP 116454b
"NASA's Kepler Spacecraft Finds 1st Alien Planet of New Mission"A water world, or ocean_planet, isn't necessarily all water: but it's covered in an ocean hundreds of kilometers deep, far deeper than Earth's ocean.
Mike Wall, Space.com (December 18, 2014)
" HIP 116454b is about 20,000 miles (32,000 kilometers) wide and is 12 times more massive than Earth, scientists said. The planet's density suggests that it is either a water world or a 'mini Neptune' with a large, thick atmosphere.
"HIP 116454b lies just 8.4 million miles (13.5 million km) from its host star, an 'orange dwarf' slightly smaller and cooler than the sun, and completes one orbit every 9.1 days. The close-orbiting planet is too hot to host life as we know it, researchers said...."
If HIP 116454b is a water world, much of its atmosphere would be water vapor: which is good at trapping heat, making it hotter than it might otherwise be.
GJ 1214 b, about 40 light years away, may be another water world: and that's another topic.
(From NASA/JPL, via Space.com, used w/o permission.)
("An artist's conception shows the size of super-Earth 55 Cancri e compared to Earth. A ground-based telescope in Spain was able to identify 55 Cancri e, which suggests that telescopes on the ground help in the search for habitable planets around other stars."
" 'Super-Earth' Alien Planet Spotted by Ground-Based Telescope, a First"We've known about 55 Canceri e since 2004, when scientists sifted out its effect on 55 Canceri from Kepler data. The next year, another scientist said that 55 Canceri e wasn't there: and what the first team had spotted was a planet with a 260-day orbit.
Calla Cofield, Space.com (December 12, 2014)
"Finding Earthlike planets beyond our solar system has largely been the work of space-based telescopes, but new observations from a remote island suggest that could change.
"The Nordic Optical Telescope on La Palma — one of the Canary Islands off the west coast of Africa — observed 55 Cancri e, a planet twice the size of Earth, as it passed in front of its parent star and caused a dip in the star's brightness, according to a new study. This is the first time a planet in this 'super-Earth' size category orbiting a sunlike star has been observed by a ground-based telescope using this detection method, the researchers say.
"First identified in 2004 by a space-based telescope, 55 Cancri e has a diameter of about 16,000 miles (26,000 kilometers) — about twice that of Earth. The alien world is eight times as massive as Earth, making it a so-called super-Earth, a planet more massive than Earth but significantly smaller than gas giants like Neptune and Uranus. While not habitable, the planet's size and position around a sunlike star make it similar to planets that might support life, researchers say...."
Turns out, they were both right, although their numbers were a tad off.
55 Canceri e whips around its star every 17 hours, 40 minutes, and a tad over 37 seconds: and 55 Canceri f every 260 days, 16 hours and 48 minutes.
The big deal with the Nordic Optical Telescope's observation of 55 Cancri is that it's on Earth: so other transiting planets can be spotted by Earth-based observatories, too.
55 Cancri is a little smaller and cooler than our sun, and roughly 40 light years away in the general direction of Asellus Borealis, another star you probably never heard of.
That picture shows orbits the Solar System's inner planets in blue, and 55 Cancri b, c, and f in black. 55 Cancri e whizzes around its star well inside 55 Cancri b's orbit.
It's a hot place: but not in the 'hot real estate deal' sense.
55 Cancri e probably has one side always facing its sun, thanks to tidal forces: the sort of thing that keeps one side of our moon facing Earth. Temperatures on its sunward side most likely are over 2,000 Kelvin, 3,140 Fahrenheit.
That's about platinum's melting point, and far above zinc's boiling point. 55 Cancri e is 'Earthlike' only in the sense that it's diameter is only twice Earth's, with between eight and 10 times Earth's mass.
That means 55 Cancri e is about as dense as Earth. If it's made of oxygen-rich compounds, like Earth, it'll be terrestrial planet: like the Solar System's inner four planets. If it's mostly carbon-rich compounds, roughly a third of the planet's mass would be carbon: including a lot of diamond.
I don't think we'll ever have diamond mines on 55 Cancri e, though. We've been making artificial industrial diamonds for a half-century: then there's shipping costs for the 40-plus light year return trip.
A message from Earth will reach the 55 Cancri system in 2044: sent from Yevpatoria's Eupatoria Planetary Radar. If there's anyone there who 'listens' on radio wavelengths, I'm not sure that they'd reply. If we have neighbors, I'm not convinced that they'd be as chatty as we are. (June 27, 2014)
With dayside temperatures above zinc's boiling point, 55 Cancri e can't support 'life as we know it:' but another planet in that system is might.
55 Cancri f is in 55 Cancri's habitable zone, where water can be a liquid. The planet is at least half as massive as Saturn: almost certainly a gas giant, with no solid surface.
Ever since the Miller–Urey experiment produced organic compounds, including amino acids, in a gaseous mix like Jupiter's atmosphere, scientists have played with the idea of Jovian life.
The idea of huge aerial jellyfish sailing the clouds of Jupiter is cool: but wildly implausible.
Jupiter has "strong vertical air circulation," convection currents like a thunderstorm's, that wouldn't let life get started. Life's chemical beginnings would get pulled down to where they'd cook, shot up to freezing cloud tops, and the cycle would repeat.
Other gas giant planet would have the same sort of turbulent atmosphere, but their moons are — yet another topic.
(From NASA/JPL, via ScienceDaily, used w/o permission.)
("Illustration of a low-mass, M dwarf star, seen from an orbiting rocky planet."
" 'Mirage Earth' exoplanets may have burned away chances for life"About three quarters of this galaxy's stars are red dwarfs, low-mass class M stars. Another 12.1 percent are more massive than red dwarfs, but smaller than our sun. There's good reason to think that planets orbiting red dwarfs couldn't support life: or that they could.
Featured Research, University of Washington, ScienceDaily (December 3, 2014)
"Planets orbiting close to low-mass stars — easily the most common stars in the universe — are prime targets in the search for extraterrestrial life. But new research led by an astronomy graduate student indicates some such planets may have long since lost their chance at hosting life because of intense heat during their formative years.
"Planets orbiting close to low-mass stars -- easily the most common stars in the universe -- are prime targets in the search for extraterrestrial life....
Besides being a majority of the stellar population, red dwarfs last a very long time: so once life got started, there wouldn't be any obvious rush to develop new forms.
On the down side, quite a few red dwarfs flare up at intervals. Before we started using electricity, and radio, the only way solar flares affected our lives was lively auroral displays.
Some red dwarfs double their brightness during flares: in a matter of minutes. It's not just light and heat: the flares emit charged particles that might chip away a planet's atmosphere.
On the other hand, if people developed on a planet whose star was a flaring red dwarf: their scientists might think that life couldn't exist without those rapid changes.
(From MPIA, V. Joergens; via Wikimedia Commons; used w/o permission.)
(Our sun, a typical red dwarf, young brown dwarf, old brown dwarf, a very cool brown dwarf, and Jupiter: all at the same scale.)
"...But in a paper to be published in the journal Astrobiology, doctoral student Rodrigo Luger and co-author Rory Barnes, a UW research assistant professor, find through computer simulations that some planets close to low-mass stars likely had their water and atmospheres burned away when they were still forming.Barnes and Luger aren't the first to show that oxygen in a planet's atmosphere doesn't necessarily come from photosynthesis. (October 18, 2013)
" 'All stars form in the collapse of a giant cloud of interstellar gas, which releases energy in the form of light as it shrinks,' Luger said. 'But because of their lower masses, and therefore lower gravities, M dwarfs take longer to fully collapse -- on the order of many hundreds of millions of years.'
" 'Planets around these stars can form within 10 million years, so they are around when the stars are still extremely bright. And that's not good for habitability, since these planets are going to initially be very hot, with surface temperatures in excess of a thousand degrees. When this happens, your oceans boil and your entire atmosphere becomes steam.'..."
(Featured Research, University of Washington, ScienceDaily)
It looks like planets that will be in a red dwarf's habitable zone once it settles down will get cooked during their formative years. Oxygen could be a sizable fraction their atmosphere: but not from photosynthesis.
Ultraviolet light from the star would the steamy atmosphere's water into hydrogen and oxygen. The lighter hydrogen atoms escape into space more easily: leaving a barren planet with oxygen in its atmosphere:
"...Luger said the working title of their paper was 'Mirage Earths.'Barnes and Luger's analysis may be an important step toward understanding where we may find life: and what assumptions to avoid as we look.
" 'Because of the oxygen they build up, they could look a lot like Earth from afar -- but if you look more closely you'll find that they're really a mirage; there's just no water there.' "
(Featured Research, University of Washington, ScienceDaily)
Other scientists have been trying to figure out why Earth is so wet. Some of it almost certainly was here from the start, part of the protoplanetary disk that became our home.
Comets apparently delivered as much as half of our planet's water after Earth formed. (December 5, 2014)
If that's the case, an Earth-size planet in a red dwarf's habitable zone might get restocked with water after its sun cooled down. That could still leave too much oxygen in the atmosphere for the earliest life to survive. (August 30, 2013)
I'm not ready to assume that red dwarf stars can't support life. We've got a great deal more to learn first.
And the more we learn, the more we find there is to know:
- "DNA Test Hype; and Studying Life's Origins"
(December 5, 2014)
- "Harpooning the 'Rubber Duck' Comet; Public Safety — and Space Aliens"
(November 7, 2014)
- "Life in the Universe, and Titan's Disappearing 'Island' "
(June 27, 2014)
- "Jadeite from Space; a Moon of Mars; and Kepler's New Mission"
(May 30, 2014)
- "Habitable Worlds, Homer, and Haldane — or — Ganymede's Oceans, and Imagining Kepler-186f's Sunsets"
(May 9, 2014)