Nell Greenfield Boyce

This is NPR.

In the fall, to recover nitrogen, trees take apart green chlorophyll.

This reveals yellow pigments that were there all along.

But the red pigments are different.

Trees make brand new red chemicals just days before a leaf is about to fall.

Nicole Hughes is a biologist at High Point University in North Carolina.

We still don't really know why some species turn red and others don't.

She says the red pigments do act as a kind of sunscreen, which may protect trees' ability to recoup that precious nitrogen.

But some researchers think the red could be a signal to insects that lay eggs in the fall.

One study found more aphids on trees with green and yellow leaves compared to trees that were red.

Nell Greenfield-Boyce, NPR News.

The telescope is the size of a school bus, and to get it into orbit over 300 miles up, it took a space shuttle.

The telescope is the size of a school bus, and to get it into orbit over 300 miles up, it took a space shuttle.

Soon after its launch in 1990, NASA discovered the telescope's primary mirror was flawed. This Hubble trouble resulted in much public mockery. But once astronauts installed corrective optics, Hubble's gorgeous images became part of popular culture on everything from lunchboxes to U-Haul rental trucks.

Soon after its launch in 1990, NASA discovered the telescope's primary mirror was flawed. This Hubble trouble resulted in much public mockery. But once astronauts installed corrective optics, Hubble's gorgeous images became part of popular culture on everything from lunchboxes to U-Haul rental trucks.

The aging observatory mostly still works great, though it's operating on just one gyroscope, and astronomers still clamor to use it. Nell Greenfield-Boyce, NPR News.

The aging observatory mostly still works great, though it's operating on just one gyroscope, and astronomers still clamor to use it. Nell Greenfield-Boyce, NPR News.

Cognitive scientists at Yale University made recordings of people speaking in a variety of contexts. Here's one from a job interview scenario.

Cognitive scientists at Yale University made recordings of people speaking in a variety of contexts. Here's one from a job interview scenario.

Then the researchers altered the recordings to create lower quality versions.