宇宙の音

Sound moves through air. Mars has thin air, so we can record real sound there.Sound is a wave that travels through air. Mars has a thin atmosphere, so a microphone on Mars can record real sound.音は空気をふるわせて伝わる波。火星にはうすい空気があるので、マイクで本物の音が録れます。

A machine feels the ground shake. We make it faster so we can hear it.A seismometer feels the ground shake. The shaking is too low for our ears, so it is sped up until we can hear it.地震計が地面のゆれを感じとります。そのままでは低すぎて聞こえないので、速くして聞こえるようにしています。

Sound cannot travel in empty space. But spacecraft catch radio waves. Scientists change them into sound.Space is almost empty, so normal sound cannot travel there. But spacecraft can catch radio waves and waves in plasma (electrically charged gas). Scientists change these waves into sound we can hear.宇宙はほとんど空っぽ（真空）なので、ふつうの音は伝わりません。でも探査機は電波や、プラズマ（電気をおびたガス）の波をとらえられます。それを人の耳に聞こえる音に変えたものです。

There is gas around this black hole, so sound waves can move. They are very low, so we made them higher.A galaxy cluster is filled with hot gas, so pressure waves (like sound) can really travel there. The waves are far too low to hear, so they were raised 57 and 58 octaves.銀河団の中は熱いガスで満たされているので、音と同じ「圧力の波」が本当に伝わります。低すぎて聞こえないので、57〜58オクターブ高くしています。

This is called sonification. Bright light becomes sound, so you can hear a space picture.This is called sonification. The brightness and position of light in a space picture are matched to pitch and volume, so you can 'hear' the picture.「ソニフィケーション（音にすること）」といいます。宇宙の写真の光の明るさや位置を、音の高さや大きさに置きかえて、写真を「聞ける」ようにしたものです。