“I think it’s a compelling argument,” says Zibi Turtle. They resemble other empty lake basins near Titan’s poles. Those specular reflections come only from two specific regions. It does rain on Titan, but not frequently enough to explain the reflections. But only lake beds would explain the timing and locations of the signals. It could be rainfall, dunes or dry lake beds. Next, they considered what might cause them. Understanding light and other forms of energy on the move After doing that, these researchers realized that the specular reflections all come from a few specific spots. Along the way, they corrected differences in the ways various observations had referred to locations on Titan. They also looked at radio data from the Cassini spacecraft. The team looked at radio data from the Arecibo Observatory in Puerto Rico and from the Green Bank Observatory in West Virginia. To solve the riddle, Hofgartner and his colleagues revisited data from several telescopes. The regions where the specular reflections show up are surprisingly dry. Those lakes and seas also are concentrated near Titan’s poles. Their liquid is not water but ethane and methane. He is a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.īut some features of Titan’s lakes and seas make them unlike those on Earth. “Titan is still currently the only other place in the universe that we know to have liquid on its surface, just like the Earth,” says Jason Hofgartner. And it did show that Titan is speckled with lakes and seas. NASA’s Cassini spacecraft offered some evidence for this. One natural explanation is that Titan has large bodies of liquid near its equator. Explainer: Understanding waves and wavelengths The waves bounce off at the same angle they went in. They occur when light waves (and radio waves are a type of light) bounce off of a flat surface in a particular way.
Those signals are called specular reflections. They were coming from the moon’s equator. Those telescopes revealed particularly bright radio signals. Astronomers at the time looked at Titan using radio telescopes on Earth. If correct, it may solve a 20-year-old mystery.
Scientists proposed the explanation June 16 in Nature Communications. Those spots, scientists say, could be the dried-up floors of ancient lakes and seas. Saturn’s moon Titan has spots around its midsection.