M. Weiss/CfA
M. Weiss/CfA

New "Super-Earth" Exoplanet May Have Water—and Life

M. Weiss/CfA
M. Weiss/CfA

A possible new Earth-like world has been found, and it’s giant, according to a study [PDF] published today in Nature. LHS 1140b, an exoplanet a mere 40 light-years away, is 40 percent larger than Earth while orbiting a tiny red dwarf star one-fifth the size of our own. That might not seem like the recipe for “Earth” or “life,” but the planet resides in its star's habitable zone, the slim "Goldilocks" orbit at which water can exist as a stable liquid. It also exhibits characteristics of a rocky world, which is significant: where there’s water and rock, there’s a possibility for life.

The world was discovered using the transit photometry method of exoplanet detection. As a planet crosses in front of a star, the star dims slightly. Think of an annular solar eclipse: When the Moon crosses in front of the Sun but is too far from the Earth to blot out the Sun entirely, the day is dimmed but isn’t plunged into darkness. The same principle applies here, though on a much finer scale. The amount the star dims also reveals its size.

So what makes this exoplanet so special? What about the TRAPPIST-1 worlds we were celebrating last month? That party might have been a bit premature. Scientists have only measured the density of one of those worlds, and turns out: It isn’t rocky. So … maybe none of the others are, either. While they’re certainly Earth-sized and in their star's habitable zone, imagining Earth without rocks is something of a challenge. LHS1140b, though, is rocks for days, and now that scientists know it's there, the plan is to study the hell out of it.

Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics and lead author of the study tells mental_floss that the team studying LHS 1140b has been allocated Hubble Space Telescope time to do another transit observation. They’ve also applied for further Hubble time and x-ray telescope time in order to assess the high-energy environment the planet may be experiencing. Here on Earth, they hope also to use both Magellan telescopes at Las Campanas Observatory in Chile, and their Chilean collaborators have applied to use three of that country’s Very Large Telescopes. "So, basically, we're hoping to throw everything we have at this planet!" he says.

The James Webb Space Telescope, set to launch next year, will really unlock the mysteries of LHS 1140b. "We hope to be able to detect not just that this planet has an atmosphere but also what it's made of. In particular, [James Webb Space Telescope] may be sensitive to carbon dioxide, water, methane, and ozone," he says. The Giant Magellan Telescope and European Extremely Large Telescope, both under construction, might be able to detect molecular oxygen as well, as the strongest features of that molecule exist at more optical wavelengths. "If we can do all of these things, we might have a pretty clear picture about the atmosphere, and what's in it, and hopefully we can even say that's very similar to the Earth's."

Dittmann's Harvard colleague David Charbonneau, a co-author of the study, tells mental_floss that until James Webb launches, there’s much work to do. "First, we need to figure out the ultraviolet emission from the star," he says. "Some red dwarfs have huge amounts of UV light, which can be devastating to the atmosphere, and life! So, we are planning to use the Hubble Space Telescope to learn that. Also, there is one (and only one) good ground-based opportunity to study the planet from Chile this fall, so we are trying to have every large telescope in Chile point at the system on that night. We are calling it Transit Night." That will take place on October 26, 2017.

While ground-based observations won't be as penetrating as what the James Webb Space Telescope will be able to do, they will tell scientists if the atmosphere has, for example, lots of hydrogen and helium ("which would make the atmosphere fluffy and easy to detect," he says) and thus not Earth-like. Once the telescopes in development go online, however, there is even a chance that they can find signs of life. "[The Giant Magellan Telescope] can detect oxygen, which is an atmospheric biosignature gas," he says, though oxygen alone isn't enough. "Maybe, unlike Earth, the oxygen is made by a different process, such as UV light breaking apart water in the atmosphere. The [James Webb Space Telescope] observations will be sensitive to the other molecules—methane, water, carbon dioxide—that would allow us to know whether the oxygen really is produced by life."

LHS 1140b was first detected by Harvard’s MEarth (pronounced "mirth") project, and confirmed by the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher. The planet is thought to be at least five billion years old, and its size and density suggest a dense iron core beneath its rocky surface.

Anne Dirkse, Flickr // CC BY-SA 2.0
10 Astonishing Things You Should Know About the Milky Way
Anne Dirkse, Flickr // CC BY-SA 2.0
Anne Dirkse, Flickr // CC BY-SA 2.0

Our little star and the tiny planets that circle it are part of a galaxy called the Milky Way. Its name comes from the Greek galaxias kyklos ("milky circle") and Latin via lactea ("milky road"). Find a remote area in a national park, miles from the nearest street light, and you'll see exactly why the name makes sense and what all the fuss is about. Above is not a sky of black, but a luminous sea of whites, blues, greens, and tans. Here are a few things you might not know about our spiraling home in the universe.


The Milky Way galaxy is about 1,000,000,000,000,000,000 kilometers (about 621,371,000,000,000,000 miles) across. Even traveling at the speed of light, it would still take you well over 100,000 years to go from one end of the galaxy to the other. So it's big. Not quite as big as space itself, which is "vastly, hugely, mind-bogglingly big," as Douglas Adams wrote, but respectably large. And that's just one galaxy. Consider how many galaxies there are in the universe: One recent estimate says 2 trillion.


artist's illustration of the milky way galaxy and its center
An artist's concept of the Milky Way and the supermassive black hole Sagittarius A* at its core.
ESA–C. Carreau

The Milky Way is a barred spiral galaxy composed of an estimated 300 billion stars, along with dust, gas, and celestial phenomena such as nebulae, all of which orbits around a hub of sorts called the Galactic Center, with a supermassive black hole called Sagittarius A* (pronounced "A-star") at its core. The bar refers to the characteristic arrangement of stars at the interior of the galaxy, with interstellar gas essentially being channeled inward to feed an interstellar nursery. There are four spiral arms of the galaxy, with the Sun residing on the inner part of a minor arm called Orion. We're located in the boondocks of the Milky Way, but that is OK. There is definitely life here, but everywhere else is a question mark. For all we know, this might be the galactic Paris.


If you looked at all the spiral galaxies in the local volume of the universe, the Milky Way wouldn't stand out as being much different than any other. "As galaxies go, the Milky Way is pretty ordinary for its type," Steve Majewski, a professor of astronomy at the University of Virginia and the principal investigator on the Apache Point Observatory Galactic Evolution Experiment (APOGEE), tells Mental Floss. "It's got a pretty regular form. It's got its usual complement of star clusters around it. It's got a supermassive black hole in the center, which most galaxies seem to indicate they have. From that point of view, the Milky Way is a pretty run-of-the-mill spiral galaxy."


On the other hand, he tells Mental Floss, spiral galaxies in general tend to be larger than most other types of galaxies. "If you did a census of all the galaxies in the universe, the Milky Way would seem rather unusual because it is very big, our type being one of the biggest kinds of galaxies that there are in the universe." From a human perspective, the most important thing about the Milky Way is that it definitely managed to produce life. If they exist, the creatures in Andromeda, the galaxy next door (see #9), probably feel the same way about their own.


John McSporran, Flickr // CC BY 2.0

We have a very close-up view of the phenomena and forces at work in the Milky Way because we live inside of it, but that internal perspective places astronomers at a disadvantage when it comes to determining a galactic pattern. "We have a nice view of the Andromeda galaxy because we can see the whole thing laid out in front of us," says Majewski. "We don't have that opportunity in the Milky Way."

To figure out its structure, astronomers have to think like band members during a football halftime show. Though spectators in the stands can easily see the letters and shapes being made on the field by the marchers, the band can't see the shapes they are making. Rather, they can only work together in some coordinated way, moving to make these patterns and motions on the field. So it is with telescopes and stars.


Interstellar dust further stymies astronomers. "That dust blocks our light, our view of the more distant parts of the Milky Way," Majewski says. "There are areas of the galaxy that are relatively obscured from view because they are behind huge columns of dust that we can't see through in the optical wavelengths that our eyes work in." To ameliorate this problem, astronomers sometimes work in longer wavelengths such as radio or infrared, which lessen the effects of the dust.


Astronomers can make pretty reasonable estimates of the mass of the galaxy by the amount of light they can see. They can count the galaxy's stars and calculate how much those stars should weigh. They can account for all the dust in the galaxy and all of the gas. And when they tally the mass of everything they can see, they find that it is far short of what is needed to account for the gravity that causes the Milky Way to spin.

In short, our Sun is about two-thirds of the way from the center of the galaxy, and astronomers know that it goes around the galaxy at about 144 miles per second. "If you calculate it based on the amount of matter interior to the orbit of the Sun, how fast we should be going around, the number you should get is around 150 or 160 kilometers [93–99 miles] per second," says Majewski. "Further out, the stars are rotating even faster than they should if you just account for what we call luminous matter. Clearly there is some other substance in the Milky Way exerting a gravitational effect. We call it dark matter."


Dark matter is a big problem in galactic studies. "In the Milky Way, we study it by looking at the orbits of stars and star clusters and satellite galaxies, and then trying to figure out how much mass do we need interior to the orbit of that thing to get it moving at the speed that we can measure," Majewski says. "And so by doing this kind of analysis for objects at different radii across the galaxy, we actually have a fairly good idea of the distribution of the dark matter in the Milky Way—and yet we still have no idea what the dark matter is."


andromeda galaxy
The Andromeda galaxy
ESA/Hubble & NASA

Sometime in the next 4 or 5 billion years, the Milky Way and Andromeda galaxies will smash into each other. The two galaxies are about the same size and have about the same number of stars, but there is no cause for alarm. "Even though there are 300 billion stars in our galaxy and a comparable number, or maybe more, in Andromeda, when they collide together, not a single star is expected to hit another star. The space between stars is that vast," says Majewski.


There are countless spacecraft and telescopes studying the Milky Way. Most famous is the Hubble Space Telescope, while other space telescopes such as Chandra, Spitzer, and Kepler are also returning data to help astronomers unlock the mysteries of our swirling patch of stars. The next landmark telescope in development is NASA's James Webb Space Telescope. It should finally launch in 2019. Meanwhile, such ambitious projects as APOGEE are working out the structure and evolution of our spiral home by doing "galactic archaeology." APOGEE is a survey of the Milky Way using spectroscopy, measuring the chemical compositions of hundreds of thousands of stars across the galaxy in great detail. The properties of stars around us are fossil evidence of their formation, which, when combined with their ages, helps astronomers understand the timeline and evolution of the galaxy we call home. 

Mysterious 'Hypatia Stone' Is Like Nothing Else in Our Solar System

In 1996, Egyptian geologist Aly Barakat discovered a tiny, one-ounce stone in the eastern Sahara. Ever since, scientists have been trying to figure out where exactly the mysterious pebble originated. As Popular Mechanics reports, it probably wasn't anywhere near Earth. A new study in Geochimica et Cosmochimica Acta finds that the micro-compounds in the rock don't match anything we've ever found in our solar system.

Scientists have known for several years that the fragment, known as the Hypatia stone, was extraterrestrial in origin. But this new study finds that it's even weirder than we thought. Led by University of Johannesburg geologists, the research team performed mineral analyses on the microdiamond-studded rock that showed that it is made of matter that predates the existence of our Sun or any of the planets in the solar system. And, its chemical composition doesn't resemble anything we've found on Earth or in comets or meteorites we have studied.

Lead researcher Jan Kramers told Popular Mechanics that the rock was likely created in the early solar nebula, a giant cloud of homogenous interstellar dust from which the Sun and its planets formed. While some of the basic materials in the pebble are found on Earth—carbon, aluminum, iron, silicon—they exist in wildly different ratios than materials we've seen before. Researchers believe the rock's microscopic diamonds were created by the shock of the impact with Earth's atmosphere or crust.

"When Hypatia was first found to be extraterrestrial, it was a sensation, but these latest results are opening up even bigger questions about its origins," as study co-author Marco Andreoli said in a press release.

The study suggests the early solar nebula may not have been as homogenous as we thought. "If Hypatia itself is not presolar, [some of its chemical] features indicate that the solar nebula wasn't the same kind of dust everywhere—which starts tugging at the generally accepted view of the formation of our solar system," Kramer said.

The researchers plan to further probe the rock's origins, hopefully solving some of the puzzles this study has presented.

[h/t Popular Mechanics]


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