Witt: Learning new things from space
Published 10:06 am Tuesday, August 21, 2018
Astronomers have made an interesting new discovery recently. Actually, a couple of interesting discoveries.
The first involves the Saraswati supercluster. A supercluster is the largest of a series of star groupings which go from galaxies to galaxy groups to clusters and then to superclusters.
One definition of a supercluster is “an unimaginably vast cosmic aggregation that collects galaxy clusters like a handful of spare change.”
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The Saraswati spans a section of the universe which is some 600 million light years (not miles) across and is estimated to contain 20 million billion suns. It is located some 4 billion light years away from Earth, which obviously means those 20 million billion suns may no longer be there since the light we are seeing from them was actually generated 4 billion years ago.
To compare — only modestly — it takes a bit more than eight minutes for light from our sun to reach earth.
Watching things in space is sort of like using H.G. Wells’ time machine, but traveling back in time rather than forward, seeing things that took place some time ago. Considering the span of Saraswati, light from a sun at one end would take 600 million years to reach a sun at the opposite end.
The other recent astronomical discovery concerns 12 new moons found orbiting Jupiter. These added 12 bring the total number of Jupiter’s moons to a whopping 79.
Imagine what it would be like if Earth had 79 moons to provide nighttime light.
Of course, many of these Jovian moons are quite small; one of those recently found is only one kilometer in diameter, just more than half a mile wide.
All these moons don’t travel in the same direction. Some are prograde, traveling in the same direction as Jupiter’s rotation, and some are retrograde, moving in the opposite direction. In fact, nine of the newly-found 12 are retrograde.
Astronomers describe one of the new moons as an oddball. It is quite small and lies in an outer orbit of the planet. It is a prograde satellite and its orbit actually crosses the orbits of several retrograde moons. This all means at some point, the oddball may actually collide with one of the other moons, an event that might be as exciting (to astronomers) as the Shoemaker-Levy comet collision with Jupiter in 1994.
Jupiter’s diameter is 11.2 times larger than the diameter of the Earth and its volume is 1,321 times larger than Earth’s. Had the Shoemaker-Levy comet crashed Earth instead of Jupiter, it would have obliterated all life on this planet.
Not a very pleasant prospect, but the Earth is a much smaller target and the solar system contains a lot of empty space, making a contact a pretty small proposition.
The orbits of Jupiter and of Earth are elliptical and the distance between the two planets varies from 629 million to 928 million kilometers. The speed of light is about 300,000 kilometers per second, so the light reflected from Jupiter takes about 32 to 52 minutes to reach Earth.
So this means if the moons collide, astronomers here won’t know about it until at least a half hour after it happens, again observing events after they have actually happened.
The universe is a vast and wondrous place, offering up new data every single day.
Wonder if all those 79 moons have been named or just given numbers. Maybe they could name the smallest one PeeWee.
Chuck Witt is a retired architect and a lifelong resident of Winchester. He can be reached at firstname.lastname@example.org.