Searching for Alien Worlds with Anjali Tripathi

What It Covers

Neil deGrasse Tyson and Matt Kirschen interview NASA exoplanet scientist Anjali Tripathi about the current state of exoplanet discovery, detection methods, habitability criteria, and upcoming missions like the Nancy Grace Roman Space Telescope and Habitable Worlds Observatory.

Key Questions Answered

• •Exoplanet catalog growth: The confirmed exoplanet count reached 5,921 as of recording and will hit 6,000 within weeks. The Nancy Grace Roman Space Telescope will add tens of thousands more using microlensing techniques when it launches within a couple years.
• •Biosignature detection evolution: Earth's atmospheric biosignatures changed dramatically over time—methane dominated four billion to two and a half billion years ago, ozone from two and a half billion to 500 million years ago, and oxygen only in the modern era, requiring telescopes to detect multiple chemical signatures.
• •Coronagraph technology advancement: The Habitable Worlds Observatory will block starlight to detect planets 10 billion times fainter than their host stars, enabling direct imaging of Earth-like worlds and spectral analysis to identify atmospheric oxygen, methane, nitrogen dioxide, and even industrial pollutants like chlorofluorocarbons.
• •Detection geometry limitations: Transit and radial velocity methods only work when planetary systems align with Earth's viewing angle. Statistical models compensate by calculating how many systems are oriented incorrectly, allowing astronomers to extrapolate the true total number of planets from detected samples.