Happy 230th Birthday, Enceladus, Our Solar System’s Greatest Hope For Life Beyond Earth
“It is still a complete unknown whether Earth is the only world in the Solar System to house any form of life: past or present. Venus and Mars may have been Earth-like for a billion years or more, and life could have arisen there early on. Frozen worlds with subsurface oceans, like Enceladus, Europa, Triton or Pluto, are completely different from Earth’s present environment, but have the same raw ingredients that could potentially lead to life as well.
Are water, energy, and the right molecules all we need for life to arise? Finding even the most basic organisms (or even the precursor components of organisms) anyplace else in the Universe would lead to a scientific revolution. A single discovered cell in the geysers of Enceladus would be the most momentous discovery of the 21st century. With the recent demise of Cassini, on the 230th anniversary of Enceladus’ discovery, the possibility of finding the incredible compels us to go back. May we be bold enough to make it so.”
On this date in 1789, William Herschel, armed with the most powerful telescope known to humanity at the time (you can get a lot of grant money when you discover the planet Uranus and name it after the King), discovered a relatively small moon of Saturn just 500 kilometers across: Enceladus. For some 200 years, Enceladus was never seen as more than a single pixel across, until the Voyager probes flew by it. What they revealed was a remarkable, unique world in all the Solar System. Now that the Cassini mission is complete, we can look back at all we know about this world, and all the signs point to a remarkable story: there’s a subsurface ocean, possibly suitable as a home for undersea life.
Is Enceladus truly our Solar System’s best hope for life beyond Earth? That’s debatable, but there’s every reason to be hopeful. Come get the story here.
Starts With A Bang Podcast #47 – Ice Giants At The Solar System’s Edge
What do we really know, and what mysteries are left to solve, about the outer worlds of our Solar System, and about the gas giant and ice giant worlds found throughout the Universe? Remarkably, if you had asked this same question 30 years ago, we would have had a quaint story about how planets form and why our Solar System has the planets it does, and we assumed that these rules would be extended to all solar systems in the galaxy and Universe. But with the deluge of exoplanet data, accompanied by better observations and simulations of our Solar System, that old story isn’t even the half of it.
I’m so lucky to get to interview Heidi Hammel for this edition of the podcast, who, as a bonus, was the lead investigator on the Hubble Space telescope when Comet Shoemaker-Levy 9 impacted Jupiter back in 1994! Come listen to one of my favorite interviews ever today!
(Image credit: NASA/Voyager 2)
Voyager’s ‘Cosmic Map’ Of Earth’s Location Is Hopelessly Wrong
“Most neutron stars don’t appear as pulsars to us, simply because their “pulses” aren’t lined up with planet Earth. But over time, pulsars can newly appear or disappear, which we’ve actually seen happen since the Voyager probes were launched. As objects rotate and orbit in space, their relative orientations change, so the pulsars that are pointing at us today won’t be pointing at us millions of years in the future. Additionally, pulsars that aren’t pointing at us today will be pointing at us in millions of years. Compound that with the fact that neutron stars adjust their rotation periods over time (via starquakes and pulsar speedup), and it’s clear that both the periods and orientations of these pulsars change dramatically over millions of years. By the time any alien picks up our pulsar map, it will be woefully out-of-date.”
When the Voyager and Pioneer spacecraft were launched, they contained a message emblazoned on them: a map of 14 pulsars, showing the location of Earth relative to them. This was a brilliant idea: showcase bright, unique identifiers, complete with their observed periods and distances from our world, and people would be able to find Earth. If we wanted to be found, it was the best idea 1977 had to offer. But 40 years later, the idea is fundamentally flawed. There are up to a billion pulsars in the Milky Way, their periods change long-term, and their orientations are variable over time, meaning they won’t be pointing at Earth in the future. If we wanted to be detected, we’d be much better off sending the same information we use to detect exoplanetary systems today!
Although it was a very clever idea presented just 10 years after the discovery of pulsars, we now know that Voyager’s cosmic map to find Earth will be hopelessly wrong by the time an alien civilization finds it.