Did TESS discover planets better than earth?
Looking up at the night sky, we can see up to thousands of stars.
Although it isn't very accurate, we can think about each star as a sort of Sun.
Since the Copernican revolution astronomers, thinkers and philosophers have been wondering
about the existence of other solar systems. Actually, it's better to call them “star
systems”. Someone should've thought: “If every star
is a Sun and if our sun has planets (as we know), it makes sense that the other stars
have planets also.” Of course, it took a lot of time to think
outside the box and start looking for other planets.
In fact, imagine being a scientist and imagine that you wanted to test your hypothesis: there
are other planets out there. How could you demonstrate it?
Where to start? Well, over time techniques were developed
and instruments were designed and perfected. Nowadays, we think that every star has a planetary
system, meaning our Milky Way Galaxy is teeming with exoplanets. Astronomers are turning their
attention to the nearest stars, those that are bright enough with enough photons so that
we may further study the planets. The nearest stars are spread all around the sky, motivating
an all-sky survey.
In April 1984, the first planetary disk was observed.
The original discovery image of a disk of dust and gas around the star Beta Pictoris
was taken with the du Pont 2.5 meter telescope at the Las Campanas Observatory in Chile.
Then, in April 1990, the Hubble space telescope was launched, starting its fundamental mission,
destined to be one of the most famous space missions of all time.
Two years later, Aleksander Wolszczan and Dale Frail announced the discovery of two
rocky planets orbiting a pulsar in the constellation of Virgo. Because they are constantly bombarded
by radiation from the dead neutron star that they orbit, these rocky planets cannot support
organic life.
But pulsars are not main sequence stars. Scientists thought that it would have been
very nice to find and see an exoplanet orbiting a main-sequence star, like our sun.
In October 1995, Didier Queloz and Michel Mayor announced their discovery of the first
planet orbiting a main-sequence star, 51 Pegasi. For this discovery, 24 years later they shared
the 2019 Nobel Prize in Physics with James Peebles.
The planet, which is half the size of Jupiter, practically gazes the surface of its star,
a revelation that baffles astronomers. Later discoveries indicated that this type of close-orbiting
planet, nicknamed a “roaster”, is a common phenomenon.
All over the years, a lot of effort was spent in order to find other exoplanets.
In particular, Kepler mission was one of the most important ones and contributed to a lot
of mindblowing new discoveries about planets, their formation and their differentiation.
We learned that planets are very different, and it seems like each of them has unique
features. There are strange planets out there.
But we noticed that there are also planets similar to the ones in the out solar system.
That's why we started to ask for more. Now, we are looking for exoplanets that are
similar to our home Earth. And, since the universe is actually homogenous
and isotropic, there's absolutely no reason to think the Earth is someway special.
This means that we could possibly find planets that are BETTER than Earth, where Better,
in this case, means “a better place to live”! Can you imagine that?
Aren't you amazed about that?
Of course, our planet will always be our first love, our mother, our home.
But, if we want to survive on the long shot as species, we have to work hard and imagine
ourselves on other planets. Of course, we are already doing small steps to reach Moon,
Mars and see what we are able to do. We hear a lot about Moon colonization, Mars
Terraformation. But what if we found a beautiful planet, let's
say, a twin planet of the Earth? Wouldn't it be nicer?
Of course, at that point, we'll probably have to deal with space travelling, but at least
we'd know somewhere out there, in a distant galaxy far far away, there is another place
like Earth. A lost twin that we desire to meet again.
And, even if we'll never manage to get there, we could spend our lives trying to understand
if some intelligent life ever existed on that exoplanet.
This would have a huge impact on science, ethics and our way of thinking.
And we can also ask ourselves if we'll ever find planets better than Earth.
That's why new missions are studying and searching for potentially habitable planets around our
Milky Way stars.
Actually, until now, if there's one thing we know for sure is that no planet is actually
better than Earth. There are, of course, some of them characterized
by – for example – the same orbital period as Earth, or maybe there are some planets
orbiting a G-V star. But the truth is that, for a planet to be habitable we need a lot
of things occurring at the same time. We need a lot of factors coming together. And we are
very far from finding planets that satisfy all the parameters.
Of course, scientists never stop dreaming. That's why Tess mission was launched: to persevere
and discover other exoplanets. To pursue the noble aim of finding Earth's lost twin.
As we can read on Tess official website:
“TESS is an MIT-led NASA mission, an all-sky survey for transiting exoplanets. Transiting
planets are those that go in front of the star as seen from the telescope and, to date,
is the most successful discovery technique for finding small exoplanets.
TESS tiles the sky with 26 segments, observing the southern hemisphere in the first year
of mission operation and the northern hemisphere in the second year. TESS has a unique, highly
elliptical cislunar orbit about Earth. With a 27.4 day observing period per segment, the
satellite is most sensitive to exoplanets with periods of less than 13 days (so that
at least two transits are used for discovery). “
The circular regions where segment overlap at the ecliptic poles have observing a period
of just over 100 days, enabling longer period planets to be discovered. These regions are
known as continuous viewing zones (CVs).
TESS anticipates the discovery of thousands of exoplanets of all sizes around a variety
of star types. It has committed to delivering 50 planets of size less than 4 Earth radii
with measured masses to the community. An international effort under the TESS Follow-up
Operations Program (TFOP) is committed to observations to distil the TESS planet candidates
down to the list of 50 with measured masses, using the best ground-based telescopes in
the world.
A little time ago, in 2020, TESS has discovered its first Earth-size planet in its star’s
habitable zone, the range of distances where conditions may be just right to allow the
presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s
Spitzer Space Telescope and have modelled the planet’s potential environments to help
inform future observations. TOI 700 d is one of only a few Earth-size
planets discovered in a star's habitable zone so far. Others include several planets in
the TRAPPIST-1 system and other worlds discovered by NASA’s Kepler Space Telescope.
“TESS was designed and launched specifically to find Earth-sized planets orbiting nearby
stars,” said Paul Hertz, astrophysics division director at NASA Headquarters in Washington.
“Planets around nearby stars are easiest to follow-up with larger telescopes in space
and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet’s
size and habitable zone status with Spitzer is another win for Spitzer as it approaches
the end of science operations this January." TOI 700 is a small, cool M dwarf star located
just over 100 light-years away in the southern constellation Dorado. It’s roughly 40% of the Sun’s
mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS
observed during the mission’s first year, and scientists caught multiple transits by
its three planets. The star was originally misclassified in the
TESS database as being more similar to our Sun, which meant the planets appeared larger
and hotter than they really are. Several researchers, including Alton Spencer, a high school student
working with members of the TESS team, identified the error.
“When we corrected the star’s parameters, the sizes of its planets dropped, and we realized
the outermost one was about the size of Earth and in the habitable zone,” said Emily Gilbert,
a graduate student at the University of Chicago. “Additionally, in 11 months of data, we
saw no flares from the star, which improves the chances TOI 700 d is habitable and makes
it easier to model its atmospheric and surface conditions.”
The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky
and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger
than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is
likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the
only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and
receives from its star 86% of the energy that the Sun provides to Earth. All of the planets
are thought to be tidally locked to their star, which means they rotate once per orbit
so that one side is constantly bathed in daylight.
Okay, we now know that TOI 700 b could be a habitable planet.
Is this all we've got?
“Before we dive in the last part of the video, please be sure to like or dislike the
video so that we can continue to improve and make these videos better for you the viewer.
Plus, be sure to subscribe to the channel clicking the bell so that you don't miss ANY
of our weekly videos."
Actually, scientists identified 24 potentially super-habitable planets. None of them met
all the criteria the researchers drew up for super-habitable planets, but one did meet
at least two — KOI 5715.01, a planet about 5.5 billion years old and 1.8 to 2.4 times
Earth's diameter orbiting an orange dwarf about 2,965 light-years away. It might have
an average surface temperature of about 4.3 degrees F (2.4 degrees C) cooler than Earth,
but if it has more greenhouse gases than Earth to trap heat, it might be super-habitable,
they said.
Another potentially super-habitable world from these 24 was KOI 5554.01, a world about
6.5 billion years old 0.72 to 1.29 times Earth's diameter orbiting a yellow dwarf about 700
light-years from Earth. We really like the average surface temperature
— about 27 degrees C [80 degrees F]! Also, it's probably about Earth's size, and
a little bit older than Earth. It could be our brother!
Unfortunately, 24 of these potentially super-habitable planets are more than 100 light-years from
Earth. This makes them too far for NASA's Transiting Exoplanet Survey Satellite (TESS) spacecraft
to capture high-quality images from to learn more about them.
But we don't have to be sad! Future spacecraft, such as NASA's James Webb
Space Telescope, NASA's LUVIOR space observatory and the European Space Agency's PLATO space
telescope, could shed light on these potentially beautiful habitable worlds.
"This video ends here! Thanks for watching everyone! Did you know about TESS? Do you
think we will ever find planets better than Earth? Let us know in the comment below!
See you next time on the channel!