Ep 4. Journey to Alien Earths

In the fourth episode of season 4 of Space's Deepest Secrets, entitled "Journey to Alien Earths," we delve into the topic of exoplanets - planets that orbit stars other than our sun. NASA has made incredible strides in discovering exoplanets, with over 4,000 confirmed discoveries to date. However, the focus of this episode is not just on finding exoplanets, but on searching for ones that are potentially habitable for life.

The episode starts by examining the history of exoplanet discovery, beginning with the first confirmed extrasolar planet that was discovered in 1992. Since then, scientists have developed incredibly advanced technology to detect exoplanets, such as the Kepler Space Telescope and the Transiting Exoplanet Survey Satellite (TESS), which are used to measure the slight dimming of a star's light as a planet passes in front of it. With these tools, scientists are able to determine the size, composition, and even potential habitability of exoplanets.

The episode then shifts focus to the search for exoplanets that may harbor life. One key factor in this search is the habitable zone, which is the range of distances from a star where a planet could have liquid water on its surface. This is a crucial factor for life as we know it, as water is essential for all known life on Earth. Scientists have identified numerous exoplanets within habitable zones, such as the potentially rocky and water-rich TRAPPIST-1 system and the more Earth-like Kepler-438b, which is located in the habitable zone of its star.

However, finding a planet within a habitable zone is only the first step in determining its potential for life. The episode investigates the process of characterizing exoplanets, which involves analyzing the planet's atmosphere to determine its composition. This is done through a process called spectroscopy, which involves studying the light that passes through an exoplanet's atmosphere as it transits in front of its star. With this method, scientists can detect the presence of certain gases, such as oxygen and methane, which are potential indicators of life.

The episode also explores alternative methods for determining habitability, such as studying the magnetic fields of exoplanets. Earth's magnetic field is crucial for protecting our atmosphere from the solar wind, which is a stream of charged particles that could strip away our atmosphere and water. By studying the magnetic fields of exoplanets, scientists can determine whether they have a similar protective shield that could promote habitability.

Lastly, the episode considers the future of exoplanet exploration. With upcoming missions such as the James Webb Space Telescope and the European Space Agency's Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, scientists will be able to gather even more detailed information on exoplanets. These missions may also bring us one step closer to discovering signs of life beyond our solar system.

Overall, "Journey to Alien Earths" provides an insightful look into the exciting and constantly evolving field of exoplanet exploration. From the technology that allows us to detect exoplanets, to the quest for finding habitable worlds, this episode highlights the incredible progress we have made in our search for life beyond Earth.