Tuesday, February 20th, 2018



What would I do without Astronomy Picture of the Day as inspiration for posts? Dominating the horizon of the bleak Australian landscape below is a sandstone formation called Uluru, fondly (by me) known as Ayers Rock.

The picture was taken shortly after sunset, and there is a blue arch rising in the east which is the earth’s shadow, bounded above by a pinkish glow or antitwilight arch. Known as the Belt of Venus, the lovely color of the antitwilight arch is due to backscattering of reddening light from the setting sun. Above the earth’s shadow is the rising full moon.

Ain’t that grand?

Ayers Rock

Before someone jumps in and compares this lump of bland, featureless sandstone with you-know-who, I quickly point out that I am proud that my namesake rock is solid, steadfast, and trustworthy, even if it is not very handsome. And very old.

Uluru is the visible tip of a massive underground rock slab, whose history goes back to sand collecting in an ancient sea bed 900 million years ago. About 300 million years ago the seas disappeared. The remaining sediment folded and fractured, lifting above sea level. Uluru is naturally grey, but the iron content of the rock is “rusting” at the surface, resulting in the distinctive red iron oxide coating. Now you know, and aren’t you glad you asked?

Dave, not willing to share his name with just any old rock.


3 Responses to “Uluru”
  1. Kyle says:

    that is a beautiful rock.

  2. Dave says:

    Well, of course!

  3. Leslie says:

    It’s a very handsome rock if I might add. I like the colors of that photo!

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!