A Futuristic Telescope design could one day let scientists
finally look at fine details of the atmosphere of Earth-sized exoplanets —
confirming if some are potentially habitable worlds. It would do so using the
gravity of the Sun and a quirk of Einsteinian physics.
The so-called “gravity telescope” would use the Sun to
examine very distant worlds, perhaps as soon as a few decades from now if the
funding, technology, and will come together in the right way, new research
shows.
Co-author and exoplanet researcher Bruce Macintosh of
Stanford University tells Inverse his team’s paper, published May 2 in The
Astrophysical Journal, builds upon decades of research by engineers and
scientists seeking to understand more about the 5,000 known planets outside of
our solar system.
HOW DOES IT WORK? — The concept of using the Sun as a
telescope is also decades old, but papers like this newly published work can
suss out more details on the initiative, he says.
The gravity telescope uses a long-established astronomical technique
called gravitational lensing. The effect happens when a massive object in the
foreground of view (like a galaxy) bends the light of a distant object in the
background (like a planet). Einstein correctly predicted this effect at least
as far back as 1936.
The paper imagines using a Hubble-class telescope at a great
distance (550 astronomical units, or Sun-Earth distances). That is relatively
close in astronomical terms but still daunting. “It's about two times further
away than Pluto, or about seven or eight times further away than the Voyager
spacecraft,” Macintosh says.
The distance of 550 AU is the focal region of the Sun’s
gravitational lens, allowing the source requiring magnification (the exoplanet)
and the lens of the Sun to align so that the telescope can see distant objects
behind, refracted by the Sun's gravity?
A four way combination photo showing a major solar flare as
it erupted from a complex sunspot group...
DIGGING INTO THE DETAILS — Macintosh cautioned that his team are not engineers, but the telescope would likely have to be equipped with a sunshield (a coronagraph) to protect it against any stray light and block out the light of the Sun. Coronagraphs are well-tested in space and are equipped on some instruments aboard the James Webb Space Telescope.
Gravitational lensing events of individual stars or planets
are usually accidental. Astronomers typically don’t know the background objects
even exist until they pop up in an archival image from a telescope happening to
gaze in that area of the sky. However, NASA’s James Webb Space Telescope plans
to deliberately exploit the technique for a recently-detected ancient star that
will be moving behind foreground members of a star cluster.
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