Sound: Some folks insist that they’ve heard meteors. And a dozen observers in Alaska emphatically told me that the Aurora Borealis was accompanied by hisses and crackles. Yet sensitive microphones set up by University of Alaska researchers in Fairbanks have never detected any sound whatsoever. In truth, the large distances (80 miles to meteors and even farther to aurorae), plus the very thin air up there, would make sounds virtually impossible. And even then it would require at least seven minutes for a noise to reach the surface. That’s a far cry from the instantaneous reports.
Call me naïve, but I believe those people. I think that some folks somehow perceive the radio waves generated by meteors as they ionize the air around them. Similarly, aurorae are often accompanied by huge electrical currents on the ground below. Such electromagnetic phenomena move at light-speed, so any noises should indeed be simultaneous. Still, how anyone’s senses could perceive this is a mystery.
Smell: To have any smell at all, atoms must cling to our nasal membranes. This is why large molecules like tetracycline or DNA have no odor: They’re too big to stick to our noses. But truly large molecules are rare outside of Earth, so that most celestial objects would indeed have some sort of scent. Unfortunately, the universe does not smell like roses. Parts of the solar system generate foul substances. Io’s volcanoes spew out putrid sulfur dioxide. Jupiter’s environment is worse than a college dorm. Uranus and Neptune are rife with methane and ammonia. No, you don’t want to go around sniffing the solar system.
Even the Moon may stink. When Michael Collins received Apollo 11’s samples, the containers had lots of lunar dust on them, which wafted into the Command Module. Collins said that it smelled awful. Then again, maybe he was really getting a whiff of Aldrin’s socks. Or perhaps the Moon is made of green cheese after all, and a government conspiracy is covering this up.
Lunar regolith (soil) is mostly silicon and oxygen, so in theory the Moon should smell like sand. However, trace materials are what often impart distinctive odors to things; so compounds like ferrous oxide, which is 12 percent of the Moon all by itself, are what probably give it a foul stench.
Touch: Is this a touchy-feely universe? Maybe a little. In addition to the 842 pounds of Moon rocks that the Apollo astronauts carried back – plus five ounces that the Soviets scooped up and returned robotically – the Stardust mission captured grains of comet Wild 2, which contained the life-friendly amino acid glycine. The allure of “hands-on” explains why meteorites are so popular.
You can touch the Moon at Washington’s Air and Space Museum, where a lunar rock is set so that you can run your fingers over it. If you could leave Earth and briefly remove your gloves, you’d find the Moon’s surface as pleasantly fine as baby powder, the Martian soil much coarser to the touch and Venus to be rock-hard and nearly red-hot. The superior planets have no surfaces at all, so you’d just be swiping at cold gas.
Bottom line: Our non-visual senses offer slim celestial pickings, and they’re not always agreeable. Looks like we’ll stick with those photons.