As astronomers become more adept at searching for, and finding, planets orbiting other stars, it's natural to wonder if anybody is looking back. Now, a team of astronomers that includes a professor from MIT has figured out just what those alien eyes might see using technologies being developed by Earth's astronomers.
According to their analysis, among other things E.T. could probably tell that our planet's surface is divided between oceans and continents, and learn a little bit about the dynamics of our weather systems.
"Maybe somebody's looking at us right now, finding out what our rotation rate is - that is, the length of our day," says Sara Seager, associate professor of physics and the Ellen Swallow Richards Associate Professor of Planetary Sciences at MIT.
Seager, along with Enric Palle and colleagues at the Instituto Astrofisica del Canarias, in Spain, and Eric Ford (MIT class of 1999) of the University of Florida, have done a detailed analysis of what astronomers here and on other worlds could learn about a planet from very distant observations, using telescopes much more powerful than those currently available to Earth's astronomers. Their study, which has just been published online in the Astrophysical Journal, will appear in the journal's print edition in April.
Most of the planets astronomers have discovered beyond the Solar System have not actually been seen; rather, they have been indirectly observed by looking at the influence they exert on stars they orbit. But even with the most advanced telescopes planned by Earth's astronomers for use over the next several years, a planet orbiting another star would only appear as a single pixel-that is, a single point of light, with no detail except its brightness and color. By comparison, a simple cellphone camera typically takes pictures with about a million pixels, or one megapixel.
"The goal of [our] project was to see how much information you can extract" from very limited data, Seager says. The team's conclusion: a great deal of information about a planet can be gleaned from that single pixel and the way it changes over time.
The way of analyzing the data that Seager and her co-authors studied would work for any world that has continents and bodies of liquid on its surface plus clouds in its atmosphere, even if those were made of very different materials on an alien world. For example, icy worlds with seas of liquid methane, like Saturn's moon Titan, or very hot worlds with oceans of molten silicate (which is solid rock on Earth), would show up similarly across the vastness of space.
However, the method depends on clouds covering only part of a planet's surface, regardless of what each world is made of. So Titan, covered by perpetual global smog, would not give up the mysteries of its weather or rotation, nor would the hellishly hot Venus, with its complete shroud of clouds.
The key, the astronomers learned after sudying data from Earth's weather satellites, is that while clouds vary from day to day, there are overall patterns that stay relatively constant, associated with where arid or rainy landmasses are. Detecting those repeating patterns would allow distant astronomers to figure out the planet's rotation period because a brightening associated with clouds above a particular continent would show up regularly once each "day," whatever the length of that day might be. Once the day's length is determined, then any variations in that period would reveal the changing weather-that is, clouds in a different place than the average.
No telescope now in operation is capable of making the measurements that Seager and her team analyzed. But planned telescopes such as NASA's Kepler, set for launch in 2009, would be able to discover dozens or hundreds of Earth-like worlds. Then even more advanced space observatories being considered, such as NASA's Terrestrial Planet Finder, would allow the followup studies to learn about these planets' rotation and weather, and the composition of their atmospheres, Seager says.
The research was funded in part by a Ramon y Cajal fellowship for Palle, and a Hubble Fellowship grant for Ford and by NASA.
Patti Richards | MIT News Office
'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics
Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences