Mars and water. Those words can trigger an avalanche of speculation, evidence, hypotheses, and theories. Mars has some water now, but it’s frozen, and most of it’s buried. There’s only a tiny bit of water vapour in the atmosphere. Evidence shows that it was much wetter in the past. In its ancient past, the planet may have had a global ocean. But was it habitable at one time?
A new study says it wasn’t. Mars lost most of its water, and it’s all to do with the planet’s size.
The search for planets beyond our Solar System (extrasolar planets) has grown by leaps and bounds in the past decade. A total of 4,514 exoplanets have been confirmed in 3,346 planetary systems, with another 7,721 candidates awaiting confirmation. At present, astrobiologists are largely focused on the “low hanging fruit” approach of looking for exoplanets that are similar in size, mass, and atmospheric composition to Earth (aka. “Earth-like.”)
However, astrobiologists are also interested in finding examples of “exotic life,” the kind that emerged under conditions that are not “Earth-like.” For example, a team of astronomers from the University of Cambridge recently conducted a study that showed how life could emerge on ocean-covered planets with hydrogen-rich atmospheres (aka. “Hycean” planets). These findings could have significant implications for exoplanet studies and the field of astrobiology.
To date, astronomers have confirmed the existence of 4,422 extrasolar planets in 3,280 star systems, with an additional 7,445 candidates awaiting confirmation. Of these, only a small fraction (165) have been terrestrial (aka. rocky) in nature and comparable in size to Earth – i.e., not “Super-Earths.” And even less have been found that are orbiting within their parent star’s circumsolar habitable zone (HZ).
In the coming years, this is likely to change when next-generation instruments (like James Webb) are able to observe smaller planets that orbit closer to their stars (which is where Earth-like planets are more likely to reside). However, according to a new study by researchers from the University of Napoli and the Italian National Institute of Astrophysics (INAF), Earth-like biospheres may be very rare for exoplanets.
In November of 2021, the James Webb Space Telescope (JWST) will make its long-awaited journey to space. This next-generation observatory will observe the cosmos using its advanced infrared suite and reveal many never-before-seen things. By 2024, it will be joined the Nancy Grace Roman Space Telescope (RST), the successor to the Hubble mission that will have 100 times Hubble’s field of view and faster observing time.
These instruments will make huge contributions to many fields of research, not the least of which is the discovery and characterization of extrasolar planets. But even with their advanced optics and capabilities, these missions will not be able to examine the surfaces of exoplanets in any detail. However, a team of the UC Santa Cruz (UCSC) and the Space Science Institute (SSI) have developed the next best thing: a tool for detecting an exoplanet surface without directly seeing it.
On Titan, Saturn’s largest moon, it rains on a regular basis. As with Earth, these rains are the result of liquid evaporating on the surface, condensing in the skies, and falling back to the surface as precipitation. On Earth, this is known as the hydrological (or water) cycle, which is an indispensable part of our climate. In Titan’s case, the same steps are all there, but it is methane that is being exchanged and not water.
In recent years, scientists have found evidence of similar patterns involving exoplanets, with everything from molten metal to lava rain! This raises the question of just how exotic the rains may be on alien worlds. Recently, a team of researchers from Havard University conducted a study where they researched how rain would differ in a diverse array of extrasolar planetary environments.
Deep inside planet Earth, there is a liquid outer core and a solid inner core that counter-rotate with each other. This creates the dynamo effect that is responsible for generating Earth’s planetary magnetic field. Also known as a magnetosphere, this field keeps our climate stable by preventing Earth’s atmosphere from being lost to space. So when studying rocky exoplanets, scientists naturally wonder if they too have magnetospheres.
Unfortunately, until we can measure an exoplanet’s magnetic fields, we are forced to infer their existence from the available evidence. This is precisely what researchers at the Sandia National Laboratories did with its Z Pulsed Power Facility (PPF). Along with their partners at the Carnegie Institution for Science, they were able to replicate the gravitational pressures of “Super-Earths” to see if they could generate magnetic fields.
“This is where we live. On a Blue Dot.” said Carl Sagan when the now famous Pale Blue Dot photo was released. Captured February 14, 1990 by the Voyager 1 Space Probe, Pale Blue Dot remains the most distant photograph of the Earth ever taken at 6 billion kilometers. This past February marked the 30th anniversary of Pale Blue Dot which was reprocessed using modern digital photo techniques creating an even more remarkable image.
Whether Pale Blue Dot, or Blue Marble, our planet is associated with the color blue. As Earth is the only inhabited world we know of, it might stand to reason that other habitable planets in space will also be blue. But it’s a little more complicated than that.
REMINDER: – Universe Today will be hosting an interview with Dr. Dirk Schulze-Makuch, co-author of the research featured in this article, on Thursday October 15th, 2020 at 8:30am PT. Click the video below to watch live or to see the recorded stream afterward
Out Earthing Earth
What planet is this?
If you said Hoth, that’s a good guess. But, it’s actually Earth depicted in one of two known “snowball” states. The entire planet’s surface was locked beneath glacial ice during the Cryogenian Period 650 million years ago and during the Huronian Glaciation 2 – 2.4 billion years ago.
Star’s can be full of surprises; some of them nasty. While our own Sun appears pretty placid, science has shown us that’s not the case. Coronal mass ejections and solar flares are the Sun’s angry side.
And the Sun has only a mild case of the flares, compared to some other stars.