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Help with Jupiter and Saturn please

  1. Mar 23, 2009 #1
    Hi. Thanks for your help. I have a Bushnell Mak Cassegrain 100mm telescope. I can focus Saturn in pretty clearly, except that I can't find the right eyepiece that would allow me to view the rings to any degree. I can see a moon around it. Also, when I focus in on Jupiter, it looks smaller than Saturn but we're closer to Jupiter and it's bigger. I can't see the red spot either. I can, however, see four moons. At least I think that's what they are. Should I be able to see more definition in the rings on Saturn and the red spot on Jupiter? I have the following eyepieces: Celestron plossl 2X barlow, 32mm, 15mm, 9mm, 6mm, 4mm; and the eyepieces that came with the telescope: 25mm and 4mm. Thanks again for any help anyone can offer. I am new to this.

  2. jcsd
  3. Mar 23, 2009 #2


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    Staff: Mentor

    Saturn's rings right now are nearly edge-on and with a 100mm aperature scope, need one of the smaller eyepieces, a 6mm or 4mm o see them and then only just barely.

    If Jupiter looks smaller than Saturn, then either you aren't looking at Jupiter or you aren't looking at Saturn (or both). Right now, Saturn is rising in the east at sunset. It is not very bright - about like an average looking star to the naked eye. Jupiter just barely clears the eastern horizon in the morning before sunrise. Perhaps one of the planets you are looking at is Venus, which is dropping fast in the western sky at sunset.
  4. Mar 25, 2009 #3
    Hi, Penny.

    Previous poster addressed Saturn....I will address Jupiter.

    Jupiter varies in distance from the earth from about 4.2 AU to 6.2 AU; right now, if I'm not mistaken, it is in a very unfavorable postion at almost the max distance, .....therefore the disk diameter will shrink accordingly (reduced by about 32% from optimal)....and the surface features will become correspondingly more indistinguishable.

    Normally at opposition (you'll have to wait about 6 months) the two equatorial belts will be discernible with a 'four incher'.....and possibly a glimpse at the red spot if optics are high quality (and atmosphere crisp) and if it is facing the earth (Jupiter rotation period is ~10 hours). The Equitorial 'bulge' will be evident.

    Furthermore; even if you ARE looking at Jupiter you are probably not going to be able to compare relative angular "sizes" unless BOTH objects are in the same field of view at the same time.
    Trying to compare object diameters visually from different FOW's is illusionary, especially since each eyepiece carries a different apparent angular field of view which makes objects "appear" larger or smaller wrt to it.

    BTW; for comparison here is a site to get an image of Jupiter as it would appear on any date.
    http://aa.usno.navy.mil/data/docs/diskmap.php [Broken]

    On Mar. 24, 2009, at 00:45 hrs. UT, for ex., Jupiter's angular diameter was 34.4 arc sec. and the red spot is visible.

    Last edited by a moderator: May 4, 2017
  5. Mar 29, 2009 #4
    Thanks so much for your reply. I appreciate it. Unfortunately, it is the 28th I'm checking this out...goodbye, red spot (haha). Is is still visible? It's sleeting here right now so I can't see anything tonight. Thanks.
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