Springtime on Mars means the thaw of carbon dioxide ice in the northern hemisphere. And when the dry ice goes, the party's over for any trapped debris that then goes tumbling down Martian cliffs in spectacular images such as this.
If you ever see a large industrial metal fire (yes, they happen) on the news, you may be surprised at what the firefighters do to extinguish it: nothing. Several metals, including lithium, sodium and magnesium, can burn easily, and from time to time large amounts catch fire in factories. But even heaps of burning metal need not cause immediate panic. They don't blow up; instead they tend to build up ash that chokes off their oxygen supply, so they slowly burn out.
The PopSci booth is hopping here at Maker Faire Austin. Here's Gray Matter columnist Theo Gray doing a version of his "dry ice cream"—this time by simply pouring liquid nitrogen into a pot of cream and sugar. Who needs an ice cream maker? Mmm mmm good.