Near Misses

Here’s a recent Google Science News headline:

NASA Alert: Airburst-Causing Asteroid Currently Headed For Earth

Now here are the basics of the story:

According to NASA’s Center for Near-Earth Object Studies (CNEOS), the asteroid that’s currently approaching Earth is known as 2020 BW13. As indicated in the agency’s database, this asteroid has an estimated diameter of about 66 feet. CNEOS noted that it is currently flying towards Earth at a speed of around 5,400 miles per hour.

And the followup:

Fortunately, CNEOS noted that 2020 BW13 is not in danger of hitting Earth during its upcoming visit. According to the agency, this asteroid will fly past Earth on Feb. 24 at 11:10 a.m. EST from a distance of 0.02333 astronomical units or roughly 2.2 million miles away.

All this accompanied by a lurid artists conception thus:

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Image: Artist illustration of an asteroid heading for the Earth Photo: Pixabay

Notice anything wrong about this illustration? A flaming asteroid is headed right for earth. Only it is still probably (my rough guess) about 100,000 miles away and thus has not struck the atmosphere, which is what would cause it to appear in flames, though only for a very brief time.

The obviously stupid illustration is still not the real problem with this report. As noted above, this particular asteroid will pass by at a distance of 2.2 million miles. An earlier report of another such object was expected to pass at 3.6 million miles! Yet Google insisted that such a close encounter was knuckle-biting nerve shattering event.

Let’s put this in perspective. To get it down to something comprehensible, scale it down so that 1 inch = 1,000 miles. At that scale, the earth would be the size of a large grapefruit -very large. That is about 8 inches in diameter. The moon would be a golf ball about 2 feet away. The asteroid in question would pass by 183 feet away. The earlier object would have passed at 300 feet away! Now imagine the earth at the center of an archery target (the preferred method to avoid traumatizing the fire arms phobics). At any respectable distance, you would be hard pressed to miss the entire target by 180-300 feet!

This isn’t science! This isn’t even junk science! It is just junk and this from the Google News service that, along with Facebook, Instagram, Twitter and the like, endlessly bloviate about fake news and accuracy. Really? We deserve better. (For more check the Google story.)

Now, approaching asteroids are a matter of concern, just not these instances. Their orbits and positions are well enough known that it is possible to point a telescope at a position and take a photo at a predetermined time and stand a good chance of capturing an image. What is so nerve shattering about that?

However, these are known as earth crossing objects, meaning that they periodically intersect the earth’s path. They are a potential threat but not right now. There are, however, two of real concern, Apophis and Bennu. Check out this headline and story from space.com.

Huge Asteroid Apophis Flies By Earth on Friday the 13th in 2029.

Apophis is much bigger than those recent objects, big enough to be called a planet killer. The greatest concern is that it might pass by at just the right point to set it up for a collision on the next pass, sometime in 2036. Mark your calendar. That might just be a real knuckle biter.

Asteroid Bennu, about half the size of Apophis, will make a close approach in 2060. It is currently under close examination from Osiris-Rex probe. A landing it planned in the near future.

Finally, the Wikipedia entry laconically notes,

On average, an asteroid with a diameter of 500 m (1,600 ft; 0.31 mi) can be expected to impact Earth about every 130,000 years or so.

Stand by…

The Beach at Peraia

Peraia, Greece, August 2019: Life on the beach of Peraia in summer is one long succession of  swimming, walking, relaxing, with leisurely lunches by the waterside. That is true for the human inhabitants. Maybe less so  for the other denizens.

IMG_20190731_234722_979The beach of Peraia is a four mile stretch of sandy beach varying in width from a few feet to a hundred or more. What sets it off from other like places is that the water is shallow well out from shore. Even as much as a hundred yards out it is possible to stand on the bottom. Though lacking in significant surf, it is still a popular recreational area and locals and foreigners alike flock here every summer.

Less recognized is the wildlife that also occupies these waters. The wide sandy bottom looks at first like an aquatic desert  but in fact there is an abundance of life to be found. It may not be a National Geographic coral reef with clouds of exotic fish but there is more to be found than meets the uncritical eye.

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Small fish abound along the beach. They seem unphased by human presence.

Stand for a moment a few yards out and watch. Very likely a number of small fish will come to investigate. Characteristically, they are elusive and well camouflaged, as are all the species here. There is little vegetation and no hiding place so species that thrive here are those that can blend in to the point of being invisible. At times those small fish seem able to bury themselves in the sand.

A note for would be fishermen: Forget your exotic tackle. No poppers, hoppers, droppers, no wooly buggers or redwing whizbangs. No spoons, spinners, none. What works for these little guys is bread. Throw a piece of bread in the water and you will start a feeding frenzy. Put a piece on your hook and expect a catch. Of course, they are barely bite size. For bigger fish, you need to get out on the water.

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A  conch snail still occupying his shell.

The keen eyed observer will ocasionally come across other oddities. Small conchs and snails are frequently found, usually by stepping on them. They are typically adorned with barnacles, the immobile barnacles taking advantage of the snails to bring them to food. Rocks of varying size are present sans barnacles, since they tend to get buried which would be unfortunate for any attached barnacles.

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This mildly perturbed Hermit crab is investigating the sudden change of scenery.

Many of the snail shells have been vacated in favor of small hermit crabs. I am not sure how the change in occupancy takes place but it is likely that the snails are the losers. Hold one of these for a minute or two and the crab will nervously investigate and sometimes try to escape.

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A razor clam shell left behind by a feeding crab(?)

A variety of shells litter the sea floor. Razor clams are present but only the empty shells will be found.  Michael was able to find a live razor clam a couple of years ago. Curiously, they were offered at a Madrid food court but there seems to be no market for them here.

Above, tiny crabs vie for exposed clams.

At the waters edge, tiny clams seem to be the choice of numerous small crabs. Since there is constant wave action (mostly from the wake of boats and ships in the bay) these clams are churned up and become crab bait. Numerous clam shells testify to their aundance -and fate. There are also tiny fish, typically about 1″ long,  frequently seen but which are so perfectly camouflaged that it takes considerable concentration to spot them.

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These little “now you see them, now you don’t fish are maybe an inch long. With an underwater camera, they are more visible. From above it is just lusck to spot them.

Of all the creatures found here, the oddest is the salp. At least, that is what I believe it is. The locals call them medusa, a generic for jellyfish, but they are not that. There are no tentacles. They are about 6″ in length and appear like a small, transparent cucumber. They pulse slowly and tend to stay near the surface. Probably filter feeders, they do not seem to have any predators.

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Salps can be elusive and difficult to photograph. It is bad enough that they are nearly transparent, but in bright sunlight and without my glasses, this is a lucky shot.

The most mysterious* aspect of them is that they will appear suddenly, a few one day, hundreds the next. And then they vanish just as suddenly. If you Google “salp”, a different creature wil be found. Out in the Mediteranean proper, they are found as long chains of individuals forming a tape like entity that can exceed 100′. These however, do not combine and merely float along, alarming the unwary and uninformed.

  • “Mysterious” is the favorite adjective of hack science writers everywhere.

The video above is probably the business end of a razor clam. The fronds appear as a black spot on the sand but when disturbed, they quickly hide.

One might think that the featureless seafloor along the Peraia beach would be bereft of life. It is anything but and a visit here will soon show otherwise. Maybe you should take a trip and swim here. You never know what might be under your feet.