What planets are transits of moons visible from a backyard telescope?

[AutoBoof]

I saw my first moon transit of GanyMede in front of Jupiter the other night (although after doing more research I think I might have just seen the shadow)

But it got me thinking, What other transits can you see from a backyard telescope?

Can you see Phobos transit in front of Mars? Any photos of this online?

Can you see any of Saturn's moons transit the planet?


Thanks,
Chris

[RickJ]

Jupiter's pole is nearly vertical to the plane of the solar system. This means that most of the time the 4 big moons pass in front of the planet each orbit. Thus you see such a transit every few days. This also means that if its rings were easily seen like those of Saturn they'd be edge on to us nearly all the time. Saturn on the other hand, like the earth, has a rather highly tilted pole. Every 15 years we see Saturn's rings edge on. For a year or so on either side of this we can see transits of Titan. Large scopes can see Rhea as well. Since it orbits closer in its window for transits are larger but I think it has closed for this cycle. Titan's last transit for this cycle was in 2010.
http://www.christone.net/astro/satur...2009/index.htm
http://www.christone.net/astro/satur...2010/index.htm

Mars, like Saturn, has a pole tilted a bit more than ours. In this case however the moons orbit so close to the planet transits happen all the time. But the moons are so small the transit isn't seen from earth. Mars orbiters have seen the transits many times however. The Mer rovers have seen the moons transit the sun in fact.

For the next 13 years or so you will have to be content with Jovian transits. These are predicted at http://www.skyandtelescope.com/. You do have to register to use the Java app.

Rick

[chornedsnorkack]

At Mars at a great opposition, 1 arc second is about 300 km. So Phobos is about 0,09x0,06 arc seconds.

At Saturn, 1 arc second is about 6500 km. So Titan should be 0,8 arc seconds, and the inner satellites less than 0,25 arc seconds.

[RickJ]

A Titan transit is quite visible in an 8" or larger scope. While size has a bearing so does contrast. Titan and its shadow have a rather high contrast against Saturn's disk and thus can be seen surprisingly easy. Rhea is exceedingly bright for its size. This makes it possible in a 10" scope as a rather starlike point against a much fainter disk of Saturn. Same as bright star can be seen against the blue sky with the naked eye if you know where to look yet the star's diameter would be measured in the thousandths of a second of arc while the ultra sharp eye can just see 1 minute of arc. These effects can be seen at the links I posted. Mar's moons carry this too far so can't be seen in transit in amateur gear.

Rick

[AutoBoof]

Interesting, Thank you guys for the replies. Ill have to wait a decade or so before I can see a saturnian moon transit for my self, But those photos should hold me over til then :-). Thanks again, This forum is a great resource.