In Praise of APOD

Almost every morning I go to one site on the Web, and almost every day I learn something new.

The site I mean is the Astronomy Picture of the Day (APOD), and day in, day out since 1995, there is a photo or a diagram or an artist’s conception of some facet of our universe.  Sponsored by NASA and Michigan Technical University, the site’s motto is: “Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer.”

I’ve only been visiting the site in the last two or three years.   I’ve found very useful the paragraph that explains each day’s photo or image. It is meticulously linked to a variety of explanatory and scientific references on the Web, and sometimes to another photo or description on APOD itself.  These sources are very helpful to a layman such as myself who has to look up what cosmology means.

Some of the photos, from such sources as the Hubble Space Telescope and arrays of huge telescopes in the clear mountain air of South or North America, are magnificent and artistic.  Here are a few like that: a photo of the three bright blue stars that make up the Belt of Orion, a photo of the Andromeda Galaxy, and another photo of a dense cluster of galaxies.  Not stars but galaxies.

This latter photo shows many, many island universes (each one composed of billions and billions of stars, as Carl Sagan used to drawl), gathered together so closely that some collide.  Now that would be something to see up close: two galaxies crashing together.  However, it’s all in slow motion… might take a million or two years to take the full measure of the occasion.

That is part of the awe of this material: the distances are so vast and the times involved so inconceivable.  It reminds me of the description of one Buddhist unit of time, the Kalpa:  A day of the god Brahma, equalling billions of human years. According to Buddha, when a piece of cloth has rubbed away a rock 16 miles high, long, and broad, one second of Kalpa is past.  These astronomical observations take in that kind of duration.  For instance, light from the most distant galaxy has taken 13 billion years to reach the Hubble telescope.

It all helps place things in perspective for me — my problems dwindle in significance every time I look at the stars, either on a summer night or on APOD.

There are a few different patterns of reporting in APOD that I’ve come to identify and enjoy.  One is about weather and different atmospheric effects here on Earth.  Here’s one with a romantic title: The Belt of Venus Over the Valley of the Moon.  The belt of Venus is a technical term describing a distinct colored band, often pink, just above the horizon in clear twilight.  (The same phenomena is seen here.)

There’s a great picture of the rarely seen green flash from the sun from 1992 in Finland.  I learned from APOD that this effect is caused by layers of the Earth’s atmosphere acting like a prism.

Here’s one of the aurora borealis observed recently in Iowa that I like a lot.  I’ve seen the northern lights in northern British Columbia and Yukon, but during periods of increased solar activity they can be seen much farther south.

If we are ever able to leave the city lights far behind us and contemplate the night, we might see something like Heaven On Earth.  In my fantasy as dictator for a day or a month, I would institute the draft, not for military purposes, but to force every young person in the country to camp out under the stars for a time sufficient to realize the mystery and wonder of existence… something the latest game console or clothing trend won’t be doing.  I’m convinced our estrangement from nature stems from the lack of such experiences.

Dismounting from the soap box, there is another pattern I’ve followed with interest: the exploits of the two robots still operating on the surface of Mars and sending back data.  Even back in 2004, Opportunity and Spirit, called rovers by NASA, had exceeded the expected time of their mission by still operating a year later.  Here you can see Spirit on the surface of Mars just caught by a recently arrived satellite two years beyond that.  There are many more such images if you search APOD’s archives.

Another thread of images relates to the mystery of “dark matter” and “dark energy” in the universe.  Most of the density of the universe can only be accounted for by what these terms attempt to describe.  I’ve been learning about the Casimir Effect and vacuum fluctuations, which have a theoretical bearing on the issue.  Astronomers have even found direct evidence that dark matter exists.  For more discussion and links, take a look at the map of the entire universe…

Another fascinating group of photos have had to do with the Cassini spacecraft, an ambitious robot spaceship which has been flying around in the vicinity of Saturn since 2004.  There’s everything from a recent photo of a hurricane on Saturn to close up photos of many of the moons of Saturn, such as Dione, to an artist’s conception of the ice volcanoes on Enceladus, another moon.  What’s more the spacecraft carried and launched the Huygen’s Probe which landed on the surface of Titan, a large enough moon of Saturn to have its own atmosphere.  It discovered riverbeds and lakebeds of what is probably methane.

I’ve put science fiction as one of the tags for this post… paradoxically, I guess, because all these discoveries and images are not fiction but once would have been, perhaps in a pulp magazine of the Fifties or even later.  And for anyone interested in writing science fiction there are richly suggestive avenues in many of the images of APOD.

Explore posts in the same categories: Photography, Science, Science Fiction