Interesting wording for this APOD. Jupiter's Rings Revealed (APOD 06 Jan 2008)
It is well known that an object/meteoroid in motion will penetrate a surface like a bullet penetrates wood but vaporize from penetrating an object unlikely. Brake up and fragment from penetrating a harder surface or rebound (ricochet), yes but vaporize, not going to happen unless there is something to cause it to vaporize. Even meteoroids go through Earth’s atmosphere, survive to penetrate a roof bounce off a photocopier and land on the floor or penetrate a roof, car trunk and land on the floor.
Adrastea is small, 23 x 20 x 15 km inside the Roche limit and inside the synchronous orbit radius. It’s almost comparable to Phobos (1.08e16 kg) in mass 1.91e16 kg.
Why didn’t Pioneer 10 in 1973 or Pioneer 11 in 1974 discover the rings?
Jupiter's Rings Revealed (APOD 06 Jan 2008)
Re: Jupiter's Rings Revealed (APOD 06 Jan 2008)
Jupiter's ring was discovered by Voyager 1 in a single image that was targeted specifically to search for a faint ring system. (1)FieryIce wrote:Why didn’t Pioneer 10 in 1973 or Pioneer 11 in 1974 discover the rings?
You'd have to set the mission looking for it in order to find it.
The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. (2)
You don't have to know the rings exist before you look for them. Looking for the unknown is the way a lot of discoveries are made. I imagine the science team thought "Is Saturn the only gas giant that has rings? Does Jupiter? Let's look while we're there."FieryIce wrote:Because you were told "Jupiter's ring was discovered by Voyager 1", how did the science team of the Voyager 1 know to look for a ring system? It just does not add up.
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NoelC
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Re: Jupiter's Rings Revealed (APOD 06 Jan 2008)
Why do you say that? And why wood? Do things in space or in the context of this particular discussion typically have the density of wood? Wood is soft and pliable. I doubt many things up there are anything like that.FieryIce wrote:It is well known that an object/meteoroid in motion will penetrate a surface like a bullet penetrates wood but vaporize from penetrating an object unlikely.
A bullet breaks up into fragments because it is going maybe 1000 miles per hour. If something hard hits something else hard going 10 or 100 times that fast, the energy released is much greater than that carried by a bullet. I see reason to think material might vaporize as a result.
And you can't compare a meteor entering the Earth's atmosphere to an impact in space, either. The Space Shuttle can re-enter the atmosphere too, dissipating the energy gradually as heat. I doubt you'd be able to recognize any part of it, however, if you slammed it into the moon at 17,000 miles per hour. You'd probably have to analyze the vapor.
-Noel