Aging stars that become red giants increase their luminosity and can wreak havoc on planets that were once in the star’s habitable zones. When the Sun becomes a red giant and expands, its habitable zone will move further outward, meaning Earth will likely lose its atmosphere, its water, and its life. But for planets further out, their time in the habitable zone will just begin.
Is there enough time for life to arise on these newly habitable planets?
The water that life knows and needs, the water that makes a world habitable, the water that acts as the universal solvent for all the myriad and fantastically complicated chemical reactions that make us different than the dirt and rocks, can only come in one form: liquid.
Our planet sits in the Habitable Zone of our Sun, the special place where water can be liquid on the surface of a world. But that’s not the only thing special about us: we also sit in the Galactic Habitable Zone, the region within the Milky Way where the rate of star formation is just right.
The European Southern Observatory’s Very Large Telescope (VLT) has a high-resolution spectrograph called ESPRESSO, designed specifically to detecting and characterize exoplanets. Astronomers recently ran a test with the instrument, studying the atmosphere and winds of Jupiter. They used a technique called Doppler velocimetry to measure the reflection of light from the Sun in the planet’s clouds, allowing for instantaneous measurement of the clouds’ wind speeds. The technique has also been used on Venus and will guide the future study of exoplanets.
The search for life is tied to the search for liquid water. That’s why astronomers are so keen on detecting rocky, Earth-like exoplanets in their stars’ habitable zones. In a habitable zone, a planet receives enough energy from its star to maintain liquid water on its surface, given the right atmospheric conditions.
But in our Solar System, we’ve found worlds with liquid water that are way beyond the habitable zone. Can we do the same in other solar systems?
A bewildering number of factors and variables led up to the planet we occupy today, where life finds a way to survive and even thrive in the most marginal conditions. The Sun is the catalyst for it all, propelling life on its journey to greater complexity with its steady fusion.
But the Sun is only benign because of Earth’s built-in protection, the magnetosphere. Both the Sun and the magnetosphere have changed over time, with each one’s strength ebbing and flowing. The Sun drives powerful space weather our way, and the magnetosphere shields the Earth.
How have these two phenomena shaped Earth’s habitability?
Saturn’s ocean moon, Enceladus, is attracting increasing attention in the search for life in our Solar System. Most of what we know about Enceladus and its ice-covered ocean comes from the Cassini mission. Cassini ended its exploration of the Saturn system in 2017, but scientists are still working through its data.
New research based on Cassini data strengthens the idea that Enceladus has the chemicals necessary for life.
Astronomers have found plenty of white dwarf stars surrounded by debris disks. Those disks are the remains of planets destroyed by the star as it evolved. But they’ve found one intact Jupiter-mass planet orbiting a white dwarf.
Are there more white dwarf planets? Can terrestrial, Earth-like planets exist around white dwarfs?
Despite the fact that we’ve discovered thousands of them, exoplanets are hard to find. And some types are harder to find than others. Naturally, some of the hardest ones to find are the ones we most want to find. What can we do?
Keep working on it, and that’s what a trio of Chinese scientists are doing.
In 1960, while preparing for the first meeting on the Search for Extraterrestrial Intelligence (SETI), legendary astronomer and SETI pioneer Dr. Frank Drake unveiled his probabilistic equation for estimating the number of possible civilizations in our galaxy – aka. The Drake Equation. A key parameter in this equation was ne, the number of planets in our galaxy capable of supporting life – aka. “habitable.” At the time, astronomers were not yet certain other stars had systems of planets. But thanks to missions like Kepler, 5523 exoplanets have been confirmed, and another 9,867 await confirmation!
Based on this data, astronomers have produced various estimates for the number of habitable planets in our galaxy – at least 100 billion, according to one estimate! In a recent study, Professor Piero Madau introduced a mathematical framework for calculating the population of habitable planets within 100 parsecs (326 light-years) of our Sun. Assuming Earth and the Solar System are representative of the norm, Madau calculated that this volume of space could contain as much as 11,000 Earth-sized terrestrial (aka. rocky) exoplanets that orbit within their stars’ habitable zones (HZs).