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Space Science

Space Weather Forecasters Can Count on Jupiter 23

Posted by timothy from the if-they-can-count-at-all-and-have-oxygen dept.
Abhishek writes "Space.com reports that forecasters who predict the Solar weather can rely on Jupiter now to help them see the part of the sun that is not visible due to Earth's rotation and revolution and sun's rotation along its own axis. Scientists observing the X-Ray emanating from the Jovian atmosphere theorised that those coming from the equator were related to solar activity but it is definitely not a perfect mirror; only one in every few thousand X-Ray photons get reflected. But even that is very useful in predicting the solar weather. 'We found that Jupiter's day-to-day disk X-rays were synchronized with the Sun's emissions,' said Anil Bhardwaj at NASA Marshall Space Flight Center, who led a new study using data from the European Space Agency's XMM-Newton telescope. Their work was detailed in Geophysical Research Letters."
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Space Weather Forecasters Can Count on Jupiter More

Space Weather Forecasters Can Count on Jupiter

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  • Scientists discover that sun still shines at night due to photons reflected from THE MOON!

  • Since Jupiter is about 43 light-minutes from the sun, and we're about 8 light-minutes away, the round-trip travel time (when Jupiter is on the opposite side of the sun) will be 43*2 + 8 = 94 minutes.

    A lot of information we get from the sun is, naturally, only 8 minutes delayed, but I guess since solar winds travel no faster than about 750 km/s (and usually travel much slower), solar winds take more than 50 hours to reach us -- so an hour and a half delay isn't that bad.

    • If Jupitor is 43 light minutes from the sun, and earth is 8 light minutes from the sun, then the correct equation for the round trip from Sun to Jupitor to Earth is: 42*2-8 which would equal 76.
      • Hahaha! 43*2-8=78! Messed up my own nit pick!

        • (Somehow, that doesn't sound right...)

          First of all, as explained elsewhere (in replies to replies of the reply you're replying to, I believe), the correct equation should be 43*2+8 (since this is helpful when Jupiter is in conjunction with the sun, and is not helpful when Jupiter is in opposition (on the opposite side of the night sky, i.e., on the same side of the sun as us). Of course, 43*2+8 = 94 minutes, which one might be tempted to write as 1 hour, 34 minutes, meaning that I'm off by 4 minutes.

          How

  • For Half of the Time, Anyway (Score:3, Insightful)

    by CheshireCatCO ( 185193 ) on Wednesday March 09, 2005 @03:21PM (#11892685) Homepage
    This is only helpful for half of the time. The other half, Jupiter would be reflecting parts of the Sun that we can see because we're on the same side.

    If monitoring the far side of the Sun (Don't you just *want* to say "dark side"?) really becomes important, we'd need a spacecraft in the same orbit as Earth, but on the opposite side of the Sun.
    • why the same orbit? we could build two (or four or eight...) and send them to a much closer orbit so that they can gather data of much higher quality
      • Obviously you could do that. But you don't get a lot of improvement in data quality by getting closer to the Sun (it's pretty well-resolved from here) and it's more expensive. Which is why I suggested one in the same orbit, not because that was the only option.
      • We have done it, and we will do it again. A while back ESA launched the two HELIOS probes into orbits getting as close as ~ 0.3 AU. Excellent missions and a lot of very important data was obtained. There are numerous proposals in the works to launch spacecraft well within the Earth's orbit. The main post was a space-weather related issue and from that perspective 1 AU is fine. But if you really want to understand the physics going in you have to get in there and measure it.
    • Currently [fourmilab.ch], the combination of Jupiter, Saturn, and Uranus do a pretty good job of covering the Sun from all angles. Of course, when the planets line up this won't work so well. But with the pole shifting [tmgnow.com] that happens during conjunction, we'll have much bigger things to worry about anyway. (WHAT?!? There was no pole shift in 2000-2001? Well, it will happen next time.)
      • Actually, there was a pole shift. It just shifted to *exactly* the same place, so no one noticed. Right? Riiiiiight.

        Seriously, the other giant planets might not be good reflectors for this purpose. Consider how dim Uranus is in the visible wavelengths, for example. It'll probably be worse in x-rays. There may only be a few options. (Venus would be my next candidate.)
    • ah, wait... I already replied to this but...
      isn't it quite hard to get something on the same orbit as earth is but on the other side of the sun?
      One would either need to slow the spacecraft down so that it ends up on the other side but that'd mean you'd need to constantly run some kind of propulsion to prevent it from crashing into the sun.
      Or you could just send it to the opposite side and somehow manage to get it into a stable orbit.

      IANSpaceCraftEngineer but to me both ways seem rather pricey in terms o
      • It's not that hard at all. You just speed it up a bit and let it use an inside track. When you get close, you hit the brakes and it moves away from the Sun a bit.

        No reason it would crash into the Sun. In fact, *that* is a terribly difficult thing to get to happen. The angular momentum/energy change needed for that is huge.

        Depending on how frugal you are with fuel, this can take a while. But it isn't all that hard.

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