NASA has discovered more than 5000 exoplanets so far, maintaining the record in the discovery of exoplanets
There was a time when we did not have much information about the planets present in our solar system, other space objects.
Then the use of advanced telescopes and technology in space research got accurate information about the planets present in our solar system. It's gone.
Now, many potentially habitable planets (exoplanets) located not only in our solar system but also in the remote regions of our galaxy have been discovered and NASA is continuing this search journey.
In this sequence, NASA has said that 'so far more than 5000 planets have been discovered outside our solar system'.
These more than 5000 planets also include many small, rocky, Earth-like planets many times larger than Jupiter.
Many are orbiting close to their star, because of this they are very hot. In addition, the discovery of some exoplanets surprised astronomers, such as the discovery of Kepler-442b (astronomers consider it more habitable than Earth, which is located at a distance of about 1206 light-years from us).
"It's not just a number," said Jesse Christiansen, science chief for the collection and a research scientist at the NASA Exoplanet Science Institute at Caltech in Pasadena.
"Each of them is a new world, a new planet. I get excited about each one because we know nothing about them."
We know this: there are hundreds of billions of such planets in our galaxy. The steady drumbeat of discovery in 1992 began with strange new worlds orbiting a stranger star.
It was a type of neutron star known as a pulsar, a rapidly spinning stellar corpse that pulsates with bursts of radiation of milliseconds.
Measuring slight changes in the timing of the pulses allowed scientists to reveal planets in orbit around the pulsar.
Finding just three planets around this spinning star essentially opened the floodgates, said the paper's lead author, Alexander Wolzhan, who unveiled the first planets to be confirmed outside our solar system, 30 years ago.
"If you can find planets around a neutron star, then planets should be basically everywhere," Volczn said. "The planetary production process has to be very robust."
Wolszczn, who still searches for exoplanets as a professor at Penn State, says we are ushering in an era of discovery that will go beyond adding new planets to the list.
The Transiting Exoplanet Survey Satellite (TESS), launched in 2018, continues to make new exoplanet discoveries.
But soon powerful next-generation telescopes and their highly sensitive instruments, starting with the recently launched James Webb Space Telescope, will capture light from exoplanets' atmospheres, reading that to identify possible signs of habitable conditions. Which gases are present?
Another Nancy Grace Roman Space Telescope after James Webb, expected to launch in 2027, will search for new exoplanets using a variety of methods.
ARIEL, an ESA (European Space Agency) mission to be launched in 2029, will observe exoplanet atmospheres; A piece of NASA technology, called CASE, will help zero in on exoplanet clouds and haze.
"To my thinking, it's inevitable that we'll find some kind of life somewhere—most likely some primitive kind," said Volszczon.
The chemistry of life on Earth and found throughout the universe, as well as the widespread detection of organic molecules, suggests that detecting life is only a matter of time, he said.
How to Find Other Worlds?
The picture didn't always look so bright. The first planet found around a Sun-like star, in 1995, turned out to be a hot Jupiter: a gas giant about half the mass of our own Jupiter in an extremely close, four-day orbit around its star.
A year on this planet, in other words, lasts only four days.
Once astronomers learned to identify them—first dozens, then hundreds—more such planets appeared in data from ground-based telescopes.
They were found using the "wobble" method: tracking the back-and-forth light-wave motions of a star, caused by the gravitational tug from the orbiting planets. But even then, nothing seemed likely to be habitable.
Finding small, rocky worlds like ours requires the next big leap in exoplanet-hunting technology: the "transit" method.
Astronomer William Borucki came up with the idea of connecting extremely sensitive light detectors to a telescope and then launching it into space.
The telescope will stare for years in a field of more than 170,000 stars, looking for tiny dips in starlight when a planet crosses the face of a star. That idea was realized at the Kepler Space Telescope.
Borucki, principal investigator of the now-retired Kepler mission, says its launch in 2009 opened a new window on the universe.
"I get a real sense of satisfaction, and wonder at what's really out there," he said. "None of us expected this huge variety of planetary systems and stars. It's just amazing."