StarDate

Messier 81


Listen Later

A perfect spiral galaxy would include a bright, round “bulge” of stars in the middle; glittering spiral arms wrapping around it; dark lanes of dust lacing through the arms; and bright star clusters sprinkled about like lights on a Christmas wreath.

In other words, it would look just like Messier 81, one of the best examples of a “grand design” spiral galaxy. It’s about 12 million light-years away, and appears close to the bowl of the Big Dipper. It’s a bit smaller and less massive than our own home galaxy, the Milky Way.

M81’s “bulge,” though, is much larger and brighter than the one in the center of the Milky Way. And the black hole in the galaxy’s heart is almost 20 times as massive as the Milky Way’s.

The spiral arms are outlined by the galaxy’s youngest, brightest stars. Over the past 600 million years or so, a major bout of starbirth has brightened the arms. That outburst is the result of gravitational interactions between M81 and two companion galaxies. The encounters compress big clouds of gas and dust. The clouds break into clumps, which then collapse to form stars – stars that make Messier 81 one of the most beautiful galaxies of all.

Under clear, dark skies, you can spot M81 with binoculars. Find the Big Dipper, which is high in the north at nightfall. M81 hangs below the bowl at that hour. It looks like an oval smudge of light that’s almost as wide as the Moon.

Script by Damond Benningfield

...more
View all episodesView all episodes
Download on the App Store

StarDateBy Billy Henry

  • 4.6
  • 4.6
  • 4.6
  • 4.6
  • 4.6

4.6

251 ratings


More shows like StarDate

View all
Radiolab by WNYC Studios

Radiolab

43,816 Listeners

The 365 Days of Astronomy by 365DaysOfAstronomy.org

The 365 Days of Astronomy

352 Listeners

Planetary Radio: Space Exploration, Astronomy and Science by The Planetary Society

Planetary Radio: Space Exploration, Astronomy and Science

1,352 Listeners

SpaceTime with Stuart Gary by Stuart Gary

SpaceTime with Stuart Gary

322 Listeners

BirdNote Daily by BirdNote

BirdNote Daily

1,225 Listeners

Ask a Spaceman! by Paul M. Sutter

Ask a Spaceman!

831 Listeners

Astronomy Cast by Fraser Cain and Dr. Pamela Gay

Astronomy Cast

2,864 Listeners

Universe Today Podcast by Fraser Cain

Universe Today Podcast

560 Listeners

Space Nuts: Astronomy Insights & Cosmic Discoveries by Professor Fred Watson and Andrew Dunkley

Space Nuts: Astronomy Insights & Cosmic Discoveries

230 Listeners

Science Friday by Science Friday and WNYC Studios

Science Friday

6,401 Listeners

Short Wave by NPR

Short Wave

6,535 Listeners

The Supermassive Podcast by The Royal Astronomical Society

The Supermassive Podcast

330 Listeners

NASA's Curious Universe by National Aeronautics and Space Administration (NASA)

NASA's Curious Universe

874 Listeners

Why This Universe? by Dan Hooper, Shalma Wegsman

Why This Universe?

392 Listeners

Crash Course Pods: The Universe by Crash Course Pods, Complexly

Crash Course Pods: The Universe

507 Listeners