2
$\begingroup$

The wikipedia article on whistlers has this information:

Voyager 1 and 2 spacecraft detected whistler-like activity in the vicinity of Jupiter known as "Jovian Whistlers", implying the presence of lightning there.

This surprised me, because this implicates a short range for detection of lightning, and I thougth atmospheric discharges produced a lot of radio noise, and so radiotelescopes on Earth should have picked signs of jovian lightning before the voyagers. As it seems not to be the case, what makes lightining hard to detect at distance?

$\endgroup$
  • $\begingroup$ You link to the wiki article. Have you read the paragraph on 'source'? It explains basically the limitations and how far the signal travels and why so. $\endgroup$ – planetmaker Aug 1 at 19:28
  • 1
    $\begingroup$ Jupiter is one of the brightest radio sources in the sky, though that power is not primarily from lightning. I don't know, but it could be that lightning on Jupiter is theoretically detectable, but the other sources of radio there are so intense that it would be drowned out. I think this is a really interesting question! $\endgroup$ – uhoh Aug 1 at 19:56
  • $\begingroup$ @planetmaker , I think that applies only to whistlers, that are easy to detect on Earth because the ionosphere acts like a resonating cavity for them, but lightning surely also radiates in other wavelenghts, not blocked from parent planetary body. $\endgroup$ – ksousa Aug 3 at 12:46
1
$\begingroup$

Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, while radio telescopes work at 30 megahertz to 300 gigahertz.

Radio telescopes would need to be 1000x larger in order to resolve the direction of extraterrestrial whistlers.

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ I don't understand your answer. The first sentence is internally consistent, but 1) lightning has prompts signals as well as producing secondary whistlers, 2) Are Jupiter's whistlers are at the same frequency as Earth's? Its magnetic field is much stronger. The second sentence is about resolving, and you don't need to resolve something to detect it necessarily. Size is important for collecting weak signals and resolution can help reject noise from the background, but is there much background to worry about? $\endgroup$ – uhoh Aug 2 at 6:08
  • 2
    $\begingroup$ I found Exo-lightning radio emission: the case study of HAT-P-11b(2017) which discusses the possibility of detecting lightning on exoplanets. I can't (pre-coffee) see if they mention detecting lightning on solar system planets using radio telescopes. $\endgroup$ – Keith McClary Aug 2 at 16:37
  • 1
    $\begingroup$ Introduction, middle of third page; "Lightning radio emission has been observed not only on Earth, but on Jupiter, Saturn, Uranus, Neptune, and potentially on Venus [e.g. Zarka and Pedersen, 1986; Gurnett et al., 1990; Rinnert et al., 1998; Fischer et al., 2006a; Russell et al., 2008; Yair, 2012]" but those are likely from nearby spacecraft. I guess Jupiter's magnetic field is only 10x stronger than Earth's so the whistlers will only be roughly 10x higher in frequency Maybe signals in deep space spacecraft can be considered radio astronomy? $\endgroup$ – uhoh Aug 2 at 17:09
  • 1
    $\begingroup$ Also in the future there will likely be low(er) frequency radio telescopes in space, I guess there's one on the far side of the Moon right now? $\endgroup$ – uhoh Aug 2 at 17:09
  • 1
    $\begingroup$ Search and Study of Planetary Lightning with UTR-2 radio telescope "The first and the only detection of Uranian Electrostatic Discharges (UED) was made by Voyager 2 spacecraft [2]. The basic characteristics of UED were defined then. In 2010 there were carried out first ground-based observations of Uranus and Venus radiation at UTR-2. Since then we have regularly provided our observations at least once per year. " I think my Answer is wrong. $\endgroup$ – Keith McClary Aug 5 at 3:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.