Astronomers discover a planet that shouldn’t be there
An international team of astronomers has discovered the most distantly orbiting planet found to date around a single, sun-like star.
Weighing in at 11 times Jupiter’s mass and orbiting its star at 650 times the average Earth-Sun distance, planet HD 106906 b is unlike anything in our own Solar System and throws a wrench in planet formation theories.
In the constellation of Leo 33.1 light years away, a Neptune-sized planet orbits a red dwarf star at a distance of 4.3 million kilometres—15 times closer than Mercury is to our sun. It’s no surprise that the planet, Gliese 436 b, has an incredibly hot surface temperature of 439 degrees Celsius, but it’s definitely a surprise that the planet is also covered in ice. Since the boiling point of water is 100 degrees Celsuis, it seems impossible for ice to exist, but Gliese 436 b’s ice isn’t exactly conventional ice as we know it on Earth. It’s a phenomenon called “hot ice”, or “ice ten”—a kind of hot, solid water. It looks a lot like our ice, but if you touched it, it would pretty much melt through your flesh. It’s not kept in a solid state by a low temperature; instead, the planet’s gravity is so powerful that it pulls all its water vapour towards the core, forcing it together into a densely-packed, solid, hot layer. Even the incredibly hot temperatures can’t evaporate or melt it. Since the ice alone isn’t enough to account for the planet’s estimated radius, it’s thought that on top is an outer layer made up of hydrogen and helium. It’s puzzling, though, because planets with hot, hydrogren-dominated atmospheres are predicted to have significant amounts of methane and no carbon monoxide—but on Gliese 436b, it’s the other way around, and we have no idea why yet.
Will Life on Planets of Red Dwarf Stars be Older & More Evolved?
“We thought we would have to search vast distances to find an Earth-like planet. Now we realize another Earth is probably in our own backyard, waiting to be spotted,” said Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA). Six percent of red-dwarf stars have habitable, Earth-sized planets, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have found. Red dwarfs are the most common stars in our galaxy; about 75 percent of the closest stars are red dwarfs. The closest Earth-like planet could be just 13 light-years away, Harvard astronomer and lead author Courtney Dressing calculated.
Red dwarf stars are smaller, cooler, and fainter than our Sun. An average red dwarf is only one-third as large and one-thousandth as bright as the Sun. The cFa team culled the Kepler catalog of 158,000 target stars to identify all the red dwarfs, then reanalyzed those stars to calculate more accurate sizes and temperatures. They found that almost all of those stars were smaller and cooler than previously thought.
Locating nearby Earth-like worlds may require a dedicated small space telescope, or a large network of ground-based telescopes. Follow-up studies with instruments like the Giant Magellan Telescope and James Webb Space Telescope could tell us whether any warm, transiting planets have an atmosphere and further probe its chemistry. Since red dwarf stars live much longer than Sun-like stars, this discovery raises the interesting possibility that life on such a planet would be much older and more evolved than life on Earth.
Courtney D. Dressing, David Charbonneau, The occurrence rate of small planets around small stars, The Astrophysical Journal, 2013, in press
Daily Galaxy via Harvard-Smithsonian Center for Astrophysics
The term ‘exoplanet’ applies to any planet outside of our solar system. At last count, we have identified 3,538.
Out of the thousands of planets we know about, some of them are incredibly bizarre compared to what we are used to seeing in our own solar system. Here are some exoplanets with very unique characteristics:
The most astounding fact about Kepler-78b is that it shouldn’t even exist, according to our current knowledge of planetary formation. It is extremely close to its star at only 550,000 miles (900,000 kilometers). As a comparison, Mercury only gets within 28.5 million miles (45.9 million kilometers) of the sun in the nearest point of orbit. With that proximity, it isn’t clear how the planet could have formed as the star was much larger when the planet formed. With its current distance, that would mean it formed inside the star, which is impossible as far as we know.
The planet itself is only slightly larger than Earth, though surface conditions are markedly different. The temperature on the surface is estimated to be 4300° F (2400° C), which is nearly nine times as hot as the temperature on Venus. Unfortunately for Kepler-78b, it is likely that the star’s gravitational pull will gradually bring the star closer and totally consume it in the next 3 billion years.
While Kepler-78b still has about 3 billion more years before getting consumed by its star, the process is well underway for WASP-12b. This exoplanet is actively getting pulled apart by its parent star, much to the delight of astronomers who can watch the process unfold. So much material has been pulled away from the planet, it has been pulled into an oblong football shape. Astronomers have estimated that WASP-12b has about 10 million more years until it is completely pulled apart by the star.
The planet is described as a “hot Jupiter” as it is a gas planet that is about 40 percent larger than Jupiter. It is currently so close to its star that it only takes 1.1 Earth days for the planet to complete a full orbit. The star, WASP-12, is G-type main sequence star, just like our own sun. It is located about 800 lightyears away in the Auriga constellation.
TrES-2b has been dubbed the “dark planet” because it does not reflect light. If we were able to view it directly, it would likely just look like a coal-black ball of gas. At 1800°F (1000°C) the planet is way too hot for clouds, which would help reflect the star’s light. The red tinges are areas of superheated gas. Other darker planets only reflect about 10% of the star’s light, but TrES-2b only reflects about 1%, making it the darkest planet ever discovered.
Why is TrES-2b so dark? Scientists aren’t quite sure. Right now, the best guess is that the majority of the planet’s composition is something like sodium or potassium which absorbs light. This dark world is located about 750 lightyears away in the Draco constellation.
HD 189773b is pretty exciting. It is relatively close, at only 63 lightyears away. It is also the first planet to have its color determined and it turned out to be a pretty blue planet, just like Earth. Unlike Earth, however, HD 189773b is a gas giant with a temperature that reaches a sweltering 1800°F (1000°C). The weather gets more extreme, because intense pressure and temperature turns silicate particles in the atmosphere into glass, which then rains down. As if that doesn’t sound dangerous enough, the winds have been estimated to gust at 4,000 mph (7,000 km/h) which really whips those glass particles around.
55 Cancri e
55 Cancri e is twice the size of Earth but is nearly 8 times more massive and twice as dense. Last fall, researchers deduced that the mass of the planet was largely carbon. Due to the pressure and surface temperature of 4892°F (2700°C) it very well could have formed diamond. It is so close to its parent star it takes a mere 18 hours for the planet to complete a full orbit.
55 Cancri e is only about 40 light-years away from us in the Cancer constellation. The parent star is much more carbon than our own sun, so it might be too surprising that planet e is also carbon-rich. From there, it isn’t much of a stretch to assume that the other four known planets in the system would also have a high carbon content.
Because of these extreme conditions, astronomers don’t believe that 55 Cancri e has an atmosphere, making it a poor candidate for the possibility for life. However, it is close enough for astronomers to use it to test hypotheses about planetary formation.
Nicknamed “Methuselah,” PSR B1620-26b is the oldest known exoplanet. The planetary system formed approximately 12.7 billion years ago, when the Milky Way galaxy was in its infancy. It is located in the Scorpius constellation about 12,400 lightyears away.
Methuselah orbits binary stars and goes around them in a circumbinary orbit. As if Methuselah’s age isn’t interesting enough, the fact that it orbits two mismatched dead stars is quite unusual. One of the stars is a pulsar and the other is a white dwarf. Since Methuselah is found in a dense star cluster, astronomers initially thought it could be a star as well, and would be considered a brown dwarf. Measurements from the Hubble would confirm that Methuselah is a planet, and it remains the oldest one we’ve ever discovered.
Located 1,400 lightyears away in the Hercules constellation, TrES-4 is the largest exoplanet we have discovered so far. Though it is over 1.7 times the size of Jupiter, it has an extremely low density and is categorized as a “puffy” planet. The planet’s density is about the same as cork, which came as quite a shock. Astronomers attribute this to extreme heat of 2,300° F (1,260° C) due to is proximity to the star. At only 4.5 million miles (7.2 million kilometers) away from its sun, TrES-4 is able to complete an orbit in three Earth days.
Gliese 436 b
30 lightyears away in the constellation Leo, Gliese 436 b is a planet that is about as massive as Neptune. The planet also happens to be covered in burning ice - though the ice isn’t anything like what we’re used to. The extreme pressure of the planet forces the water to stay in solid form, even though the temperature exceeds 570° F (300° C). The outer layer of the solid water is superheated and comes off as vapor. Water has over 10 solid states, not including common ice.
In its present position, the water would not have been able to condense down into a solid, indicating that it migrated toward its sun after it formed.
The late Carl Sagan once asked this question, “What does it mean for a civilization to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical civilization is a few hundred years old… an advanced civilization millions of years old is as much beyond us as we are beyond a bush baby or a macaque.”
Although any conjecture about such advanced civilizations is a matter of sheer speculation, one can still use the laws of physics to place upper and lower limits on these civilizations. In particular, now that the laws of quantum field theory, general relativity, thermodynamics, etc. are fairly well-established, physics can impose broad physical bounds which constrain the parameters of these civilizations.
This question is no longer a matter of idle speculation. Soon, humanity may face an existential shock as the current list of a dozen Jupiter-sized extra-solar planets swells to hundreds of earth-sized planets, almost identical twins of our celestial homeland. This may usher in a new era in our relationship with the universe: we will never see the night sky in the same way ever again, realizing that scientists may eventually compile an encyclopedia identifying the precise co-ordinates of perhaps hundreds of earth-like planets.
This timelapse video captures the past 10 years’ worth of weather as seen by the GEOS-12 satellite during its service. It’s a mesmerizing look at the large-scale convective flow of Earth’s atmosphere. The prevailing winds for each region are clear from the motion of the clouds, but short-term effects are visible as well. June through November marks the Atlantic hurricane season, and you can see as storm after storm gets generated near western Africa and shoots westward toward North and Central America. You can also see the pattern tracks of these storms in these maps, which show 170 years’ worth of worldwide hurricane tracks. (Video credit: NOAA; via Scientific American)
The terrain is very different than the near side and recently UC Santa Cruz researchers published a study as to why that is. They theorize that there was a “giant splat" from an ancient smaller moon that caused this feature:
"The mountainous region on the far side of the moon, known as the lunar farside highlands, may be the solid remains of a collision with a smaller companion moon. The near side is relatively low and flat, while the topography of the far side is high and mountainous, with a much thicker crust. A Mars-sized object collided with Earth early in the history of the solar system and ejected debris that coalesced to form the moon. The study suggests that this giant impact also created another, smaller body, initially sharing an orbit with the moon, that eventually fell back onto the moon and coated one side with an extra layer of solid crust tens of kilometers thick."
The Cosmos extends, for all practical purposes, forever. After a brief sedentary hiatus, we are resuming our ancient nomadic way of life. Our remote descendants, safely arrayed on many worlds throughout the Solar System and beyond, will be unified by their common heritage, by their regard for their home planet, and by the knowledge that, whatever other life may be, the only humans in all the Universe come from Earth. They will gaze up and strain to find the blue dot in their skies. They will love it no less for its obscurity and fragility. They will marvel at how vulnerable the repository of all our potential once was, how perilous our infancy, how humble our beginnings, how many rivers we had to cross before we found our way.