Starry Eyed Dimensions

By The Metric Maven

Bulldog Edition

My friend Dr Sunshine is very good at expressing and interpreting numbers. He has a favorite example from Star Trek IV: The Voyage Home (1986) that he uses to illustrate numerical importance:

Spock: [in response to Kirk pawning his antique spectacles from Wrath of Khan] Excuse me, Admiral. But weren’t those a birthday gift from Dr. McCoy?

Kirk: And they will be again, that’s the beauty of it.

[to Antique Store Owner]

Kirk: How much?

Antique Store Owner: Well, they’d be worth more if the lenses were intact. I’ll give you one hundred dollars for them.

Kirk: …Is that a lot?

Recently the farthest star ever viewed by a telescope was sighted. Phil Plait, Bad Astronomer, and worse metric user, attempted to impress his audience by saying:

This is incredible: Due to a quirk of cosmic geometry, astronomers have detected the light from the farthest individual star ever seen. How far away is it?

Over nine billion light-years away.

Yes, you read that right. Nine. Billion. Light-years.

A single star, from that distance. Holy yikes. Seriously, when I read about this the hairs on the back of my neck stood up. This is seriously amazing, so much so that for a moment I couldn’t believe it was real. Then I read the paper, played with the math a little, and, sure enough, this appears legit.

I was immediately uncertain just how far away this star is. A billion light years?—is that a lot? In my essay Long Distance Voyager, I use metric prefixes to categorize different astronomical items:

click to enlarge

I define nearby stars as those measured in Petameters (1015), and far away when measured with Exameters (1018). Long ago it stuck in my brain that the observable universe has a dimension that is in Yottameters (1024). So just how big is 9 billion light years? Well, knowing that a light-year is 9.4607 Petameters we multiply this by 9 billion (Giga-) and obtain 85 Yottameters! Wow, that is big. The farthest detected galaxy is about 126 Yottameters, and the diameter of the observable universe is about 880 Yottameters! This is one serious Yottasurprise. We can see two metric triads farther than the metric definition of far away stars! How on Earth, or actually how in the universe, did this happen?

Well, it is an interesting coincidence that allowed it. The star would normally be too faint to see, but a cluster of galaxies between the star and ourselves acts as a gravitational lens, which concentrates the light from that star enough for us to see it. Not only can we see it, the star has been identified as a blue supergiant, which is one of the brightest type of stars known. Rigel in the Orion constellation (lower right star) is a blue supergiant, but is at a distance of only about 8 Exameters from us. Deneb is 24 Exameters from us. One of the farthest stars ever seen is UDF 2457, which is 558 Exameters away; whereas the just discovered Lensed Star 1 (LS1) is 85 000 000 Exameters distant. The human eye can only detect a minute number of stars which are only about 10 Exameters from us, beyond that, individual stars fade into the blackness, hidden from our unaided gaze. Galileo was amazed at the number of normally invisible stars that his telescope allowed him to suddenly see. Keep in mind that our Galaxy is only about 1000 Exameters across, all the stars you see with your eyes are essentially local.

Einstein asserted that a large mass literally warps space. The closer one is to the large mass, the larger the amount of warping. On May 29, 1919, a group led by Arthur Eddington (1882-1944) and Frank Dyson (1868-1939) took a photograph during a total solar eclipse. Stars near the Sun changed their position with respect to stars further away. When images of the stars, taken when the Sun was absent, was placed over one taken by Eddington’s group during the eclipse, stars near the Sun were seen to be in a different position than those radially further away, and therefore less influenced by the Sun’s gravity. This bending of light has important uses in astronomy. When searching for planets that might have been ejected from their home solar systems into space, astronomers watch for a light-warped signature that a planet produces when passing in front of a star. In the case of LS1, lensing distortion occurs as it orbits around the center of the galaxy where it resides. The location of the individual galaxies that make up the “lensing cluster” are not homogeneous which also introduce undesired aberration.

The cluster of galaxies happen to be located in positions that add together (most of the time) in a way to capture and concentrate the light from this single star, and allow us to see an extra two metric triads (1 000 000) further in distance than is normally possible. Is that alot?—YES!


Postscript: On 2017-08-24 Bad Astronomy posted an essay titled: A 500 TRILLION KM LONG STREAMER OF AMMONIA IN ORION. Is that a lot? Well, 500 Trillion Km is 500 Petameters, or a length that encompasses a distance to nearby stars in our own galaxy. When one uses Ye Olde English Prefixes with metric, it’s not even pigfish, it’s just fishy.


The Metric Maven has published a book titled The Dimensions of The Cosmos. It examines the basic quantities of the world from yocto to Yotta with a mixture of scientific anecdotes and may be purchased here.

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