Last Updated on February 26, 2025 by Ecologica Life
Did you know that small planets are abundant in the Milky Way galaxy? Astronomers are constantly discovering more and more of them in our cosmic backyard. These planets are of particular interest to astronomers because they may hold some of the best chances of finding life like our own.
One place you might look for signs of life is on extremely old planets, as they theoretically have had the longest time frame for life to evolve. In this article, we will talk about the discovery of TO1-561b, an extremely old and interesting planet.
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Table of Contents
Introduction
For decades, astronomers have searched the cosmos for planets that resemble Earth, looking for clues to habitability beyond our solar system. In a landmark discovery, scientists have identified one of the oldest known Earth-like exoplanets, estimated to be more than 10 billion years old – twice the age of our own planet. This raises intriguing questions: Could such an ancient planet like this support life? What does its longevity tell us about planetary habitability and evolution?
The Discovery
How Was It Found?
The newly identified planet, designated TOI-561b, was detected using NASA’s Transiting Exoplanet Survey Satellite (TESS) and confirmed by data from the Keck Observatory in Hawaii. It orbits a metal-poor star in an ancient part of the Milky Way known as the Galactic Thick Disk, an area thought to contain some of the oldest stars in the universe. The planet is located some 275 light years away from Earth, which means it takes light from that solar system nearly 300 years to reach us.
TO1-561b Facts
- Age: At over 10 billion years old, TOI-561b is among the oldest rocky planets ever discovered.
- Size: It is slightly larger than the Earth, with a radius of 1.45 times that of our planet.
- Orbit: It orbits its star in less than 12 hours, which means that 1 year there is half a day for us.
- Temperature: Due to its proximity to its star, surface temperatures exceed 1,700ºC (3,100 ºF), making liquid water – and therefore, Earth-like life – unlikely.
- Water: Despite the temperature, TO1-561b is likely to have a significant amount of water that has evaporated into a puffy steam atmosphere.
Why The Strange Name?
The name “TOI-561B” might look unusual, but it follows a systematic naming convention used for exoplanets discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS).
- TOI stands for TESS Object of Interest. This means that the planet was first flagged as a potential exoplanet by TESS.
- The number 561 is a sequential identifier assigned to the host star in the TESS catalogue.
- The letter b indicates that this is the first planet discovered orbiting that particular star (the star is considered component A, and subsequent planets would be labelled c, d, etc).
So, “TOI-561b” is a technical name that tells astronomers both where the object came from (TESS) and the order in which it was discovered around its host star.
Can a Planet This Old Support Life?
1. Could Life Have Existed in the Past?
Although TOI-561b is now a scorched world, its ancient nature raises an intriguing possibility: Did it once have more hospitable conditions? Billions of years ago, the planet may have been cooler, with the potential for liquid water before its host star evolved and intensified in brightness.
2. The Role of Ancient Planets in Habitability
Most known exoplanets are relatively young, making TOI-561b an exceptionally rare case study in planetary longevity. Its existence suggests that rocky planets can remain stable for billions of years, possibly providing extended windows for life to emerge and evolve elsewhere in the galaxy.
3. Metal-Poor Worlds: Can They Support Complex Life?
One of the biggest puzzles in astrobiology is whether life requires a planet rich in heavy elements such as iron and oxygen. TOI-561b’s host star is metal-poor, meaning that planets forming in this system may lack key ingredients for life as we know it. However, some scientists argue that life could emerge under different chemical conditions to those found on Earth.
Implications for the Search for Life
1. The Oldest Habitable Planets May Be Yet to Be Found
This discovery suggests that ancient Earth-like planets may be common throughout the galaxy, many of which may have maintained habitable conditions for longer periods than Earth.
2. Expanding Our Understanding of Planetary Evolution
The discovery challenges existing models of the evolution of rocky planets. Understanding how TOI-561b formed and survived for so long could change the way scientists think about planetary lifespans.
3. A Step Closer to Finding ‘Earth 2.0’?
No one here is suggesting that we should prioritise finding a new Earth over taking care of this one. But statistically, there is a good chance that an Earth 2.0 exists. While TOI-561b is unlikely to be habitable today, it demonstrates that rocky planets can exist for billions of years – potentially allowing for the discovery of similar planets that still have the right conditions for life.
Conclusion
TO1-561b is more than just an ancient exoplanet – it’s a window into the past of our galaxy. Its existence suggests that planets can remain stable for eons, potentially sustaining life for longer than previously thought. While this particular world may be too hot for life as we know it, the discovery raises hopes that other ancient Earth-like planets may still be out there, waiting to be found.
The search for habitable worlds continues, and with each new discovery, brings us one step closer to answering one of humanity’s greatest questions: Are we alone in the universe?
What Do You Think?
Could an ancient planet like TOI-561b have supported life in the distant past? What does this discovery mean for our understanding of planetary evolution? Let us know in the comments!
Bibliography
- Weiss, L. M., et al. (2021). The TOI-561 System: An Ultra-Short-Period Rocky Planet and Two Mini-Neptunes Orbiting an Old, Metal-Poor Star. The Astronomical Journal.
- NASA Exoplanet Archive. (2023). TOI-561b Planetary Data. Retrieved from https://exoplanets.nasa.gov.
