Scientists have recently discovered an exoplanet which lies closer to Earth than ever before – within just four light-years and within its star’s habitable zone, where liquid water could potentially exist on its surface.
Planet 95% the size of our own Earth would likely be composed of rocks and soil; it likely orbits a red dwarf which could pose problems to life there.
Proxima Centauri
Astronomers are delighted to report that Proxima Centauri may harbor a planet within its habitable zone – meaning liquid water could exist on its surface! This discovery marks years of scrutiny of Proxima Centauri as red dwarf. Proxima b, known as its name implies, orbits within this range where liquid water could exist on a planet’s surface.
Proxima Centauri light curves revealed evidence of a planet orbiting it tidally locked with Proxima Centauri; after conducting an in-depth, months-long observational campaign in early 2016, they detected evidence of its gravitational pull from Proxima Centauri which produced a subtle periodic wobble, consistent with smaller planets tugging on it via their gravity; though smaller planets produce smaller, imperceptible wobbles that may be harder to detect, this one was robust enough for detection with precise measurements being made necessary in order to confirm its existence and determine its position within its star’s system.
Astronomers using data from the High Accuracy Radial Velocity Planet Searcher (HARPS) instrument at La Silla Observatory at European Southern Observatory calculated the mass, radius and orbital period of this newly discovered planet. Based on their calculations they concluded it has a minimum mass of 1.3 Earth masses with an approximate radius of 0.05 astronomical units making it one of the smallest exoplanets ever discovered – its orbital period being 11.2 days placing it squarely within its star’s habitable zone.
Although tidally locked planets are generally considered hostile environments, Proxima b may actually prove more habitable than expected thanks to winds distributing heat and mitigating extreme temperatures on its star-facing side. Furthermore, while Proxima B now appears relatively peaceful and quiet compared to when it first formed as its star once emitted intense flares that could have spread harmful radiation across any unprotected planets nearby.
Astronomers will then observe transits, or instances in which the planet passes in front of its star as seen from Earth. This allows astronomers to accurately measure its size, confirm that it is composed of rock, and assess what material its atmosphere consists of. Over time, ground-based observatories such as Thirty Meter Telescope and Giant Magellan Telescope will eventually image this distant world in great detail while space-based Wide Field Infrared Survey Telescope, expected to launch sometime during 2030s will image it further still.
OGLE-2005-BLG-390Lb
So far, only a handful of exoplanets with orbits shorter than one year have been discovered at distance from their stars. But OGLE-2005-BLG-390Lb, with five times Earth’s mass and twice its diameter, is one of the first exoplanets discovered at such an extreme distance; and is one of the closest Earth-like planets yet found. The planet lies 20,000 light years away in Sagittarius near the Milky Way galaxy’s center. It was identified through gravitational microlensing – a technique in which light from one background star is bent and magnified by gravity acting on another nearby star – to discover it. Astronomers from 32 institutions worldwide took part in this observation campaign led by Keith Horne from St Andrews University and detected on August 10 by the PLANET/RoboNet telescope network – including Danish 1.54m telescope located at ESO La Silla in Chile.
Researchers were able to measure both the size of a lensing star, or brown dwarf, and its orbital period and eccentricity. A planet was discovered – known as OGLE-2005-BLG-390Lb – approximately 2.5 to 4.1 AU away, or approximately the distance between Mars and Jupiter in our Solar System.
Due to its large orbit and cool parent star, due to which its surface temperature should likely reach 220 degrees Celsius below zero. Therefore, this planet more closely resembles Uranus and Neptune than Venus and Earth.
Astronomers hope to gain more insights into the formation of this planet by watching its host star over time and using the James Webb Space Telescope to examine its atmosphere – giving astronomers a unique opportunity to examine composition and surface features as well as potential hosting of life forms. Astronomers are excited about this discovery which could potentially lead to extraterrestrial life being discovered here in our own galaxy; an extraterrestrial life discovery would represent a huge step in their search and could help explain how humankind might have survived under harsh outer space conditions by understanding our own origins!
TRAPPIST-1
Last year, astronomers discovered seven Earth-sized planets orbiting a dwarf star located less than 40 light-years away in Aquarius constellation. This discovery marks an exciting breakthrough in exoplanet research; three of these seven planets fall within their parent star’s habitable zone and could potentially support liquid water on their surfaces; however it’s yet unclear whether any have atmospheres that might host life forms.
Astronomers discovered TRAPPIST-1 planets using transit observations, which allow astronomers to see its light dim as it passes in front of its host star. Subsequent studies using ground and space-based telescopes have helped astronomers narrow down each planet’s size, mass, radius and atmospheric constraints on some. Furthermore, this new study published in Nature provides further details on their composition as well as interactions with their hosts stars.
According to the study, all of the planets in TRAPPIST-1 system are composed of rock material; with the possible exception of TRAPPIST-1e which may be closest in terms of size, mass and radii to Earth-sized planet. TRAPPIST-1e appears to possess only a thin atmosphere and might even possess some trace amounts of surface water, according to astronomers.
TRAPPIST-1f and TRAPPIST-1g are further away, making it more difficult to determine whether they have atmospheres or surface water. However, their densities – now more accurately understood than before – indicate they could contain up to five percent of their mass as water bodies (250 times greater than Earth).
Astronomers used the Hubble Space Telescope to observe seven planets’ interactions with their host stars, specifically how they reflect and scatter starlight. Astronomers took advantage of how the planets’ short orbital periods allow them to be tidally locked with one host star at any one time – making their movement appear almost clockwork like.
Gliese 667Cc
Gliese 667Cc is one of three planets found orbiting Scorpius 22 light years away and forming part of a triple star system with habitable zones encompassing this star system, or triplet star systems. Gliese 667Cc is a super-Earth planet (more massive than Earth but smaller than gas giants such as Uranus or Neptune), orbiting within this habitable zone for its host star; marking the first time such planets have ever been discovered within such zones in one system!
Astronomers were able to detect Gliese 667Cc through studying how its star “wobbled” as its orbit was altered by planet Gliese 667Cc, providing insight into its size, mass, orbital period and orbital wobble. Their team used the telescope at European Southern Observatory’s 3.6-meter HARPS instrument in Chile together with observations from other observatories to do their work.
Guillem Anglada-Escude of the University of Gottingen in Germany and Mikko Tuomi from Hertfordshire University in United Kingdom were among those who examined new data from HARPS. Their study confirmed the existence of Gliese 667Cc as well as showing it has similar density to Earth, suggesting it likely has dense atmosphere and is possibly water planet.
Astronomers also discovered that Earth was tidally locked to its star, meaning one side always faces its star and the other perpetually dark; thus leading to no seasonal cycles on this planet.
Gliese 667Cc’s discovery by astronomers has opened up new opportunities to locate potentially habitable exoplanets in this part of the galaxy, previously it had only been possible to detect distant exoplanets. Astronomers now intend to investigate whether any distant stars host Earth-like planets in their habitable zones; for this, new instruments must be created which detect them over a greater orbital period range; until that happens, searching for potential habitable planets remains both exciting and daunting!