Amateur astronomy; Observing the planets

Factual Questions
1

A few months back I purchased a 6-inch SkyWatcher Dobsonian, my first telescope. I am armed with the 25mm and 10mm eyepeices that come with it, plus a 2X Barlow lens that I assume is cheap but it seems to work okay. This effectively gives me magnifications of 48, 96, 120 and 240.

So far the scope works fine - great, actually. I’ve spotted and identified nebulas, galaxies, the works. One gripe I do have, however, is that I can’t resolve any detail on Jupiter except that I can see two horizontal lines. The planet appears way too bright - it’s a brilliant white disk, too bright for detail. (For that matter I’m getting no detail on Saturn or its rings, but that’s to be expected.)

Is this the best level of detail I can expect with this instrument, or would a different filter help? Are the eyepeices too cheap? I have a no. 56 filter that appears to do absolutely nothing.

2

Rickjay,

I am an amateur myself. While I can’t help your specific question (my best guess would be yes, a filter will help) I am mostly curious as to where you purchased your telescope? Did you buy it online or at a walk in store? Do you mind if I ask what it set you back?

3

bernse, I purchased my scope at Efstonscience in Toronto, ON, which is a very respected science and astronomy retailer. The scope, with lenses and stand, cost $399 CDN, plus I shelled out another $120 or so on some other accessories, like a Telrad finder, a red flashlight, the no. 56 filter, and some books.

If I were going to do it again I’d pay an extra $200 and get an 8-inch scope, but that’s with benefit of hindsight; at the time I wasn’t sure if I’d stick with the hobby, so I wanted to limit my initial investment. As it turns out, now that I’m into it I get more interested in it every day, so now I want a bigger scope. I’m going to wait a few years, though, and save for a Meade scope with all the bells and whistles.

4

Thanks Rick. I found their website. http://www.e-sci.com/telescopes/5/1024/1043/10600.html has my interest.

5

You can try a neutral density filter, to tone the brightness down a bit, but I think you’ll find this dosn’t help with the contrast, which is part of what’s keeping you from seeing more details. You might want to play around with colored filters, which can be helpful in bringing out subtle details; Orion Telescope Center sells some sets for reasonable prices.

But the most important part of seeing details on planets involves magnification and seeing conditions - don’t be afraid to use high magnifications, and be prepared to watch the planets for a LONG time. Often, seeing subtle details is a “one or two second” sort of thing; the turbulence in the atmosphere settled down for a brief instant, and you get a good glimpse for a few seconds, then it starts playing up again and the subtle details once more become a blur. You have to be willing to wait patiently for those infrequent brief seconds of perfect seeing to see the subtle features on the planets.

And whatever you do in the future, hang on to your 6" dob! It’s a teriffically handy size, easy to set up in a hurry, and just perfect for those weekday nights when you just want to pop outside for a quick hour or so of casual observing. You’ll find that you’ll still use that 6" scope even after you buy your larger “dream scope”.

6

I second everything artemis said. I seem to recall that blue and green filters sometimes helps for Jupiter, but finding a calm moment is more important. Even professional astronomers have to deal with atmospheric conditions - on some days the air just isn’t calm enough and we can’t get good data.

Also, are you letting the telescope cool down to ambient temperature? A warm telescope in cold air generates its own turbulence, and the optics would be distorted by the temperature gradient. Let it sit outside for an hour before observing.

You might also want to look up when the Red Spot would be visible. Besides the two dark bands, that’s the feature you’re most likely to be able to see. IIRC most astronomy magazines and many planetarium software display this info.

7

Mr. Athena is a Certified Telescope Geek, and I asked him your question. Basically, what you asked boiled down to “Should I be able to see detail on Jupiter with my scope?” His answer? “Maybe.”

There’s a whole pile of things going on here. First and foremost, seeing conditions. If it’s windy or humid or dry or whatever, that’s going to affect your views. Turbulance is your enemy - it will make the planet go from being highly detailed to a bright fuzzball. Another factor is how high Jupiter is in the sky - in general, the higher up, the more detail you should see.

Second: Your scope. A SkyWatcher is a decent scope. However, mirror qualities vary, both the primary and secondary. A lot of great seeing is due to very high quality mirrors. I’m assuming you’re not going to run out and spend $5-10K on a top end scope with a to-die-for mirror, so there’s a few other things you can look at. Is it collimated correctly? Mirrors dirty? (be careful cleaning 'em if they are). Scope set up correctly?

I don’t think a filter is the answer. Mr. Athena regularly gets awesome views of the planets with his 12.5" and 20" Dobs, and he doesn’t use any filters. Given than both of those scopes let in WAY more light than your 6", if a filter was needed, he’d have to have one.

I agree with Artemis about just watching for a while. You always just stare at the planet for a while, and DING! all of a sudden it springs into detail. Just as fast, it’s gone. Be patient.

scr4 also brings up a good point - cool down. Turn your scope so it points straight up, and let it cool for a minimum of 30 minutes, better to go for an hour, for the reasons he states.

And also, speaking of Meade scopes with all the bells and whistles - we’ve had several Meades, from the low end Maksutovs to 7" Macs to at least 2 12" Schmidts. We’ve also been through the whole refractor thing, with Astro-Physics and other brands of refractors. I’m guessing Mr. Athena’s had at least 10, maybe more, scopes in the last 2-3 years. (yes, he’s insane, thanks for asking). But the ones that have consistently been the easiest to set up and use and consistently give the best results are the Dobs, and he’s pretty much settled on them. Don’t be too quick to go get that Meade.

8

Thanks for the advice on the Meade, Athena. A 20" Dob might be a little impractical without a larger vehicle, though. I have to drive out of the city for good seeing. :slight_smile: I am pretty careful to let the scope cool down and such before viewing. It seems to be collimated, at least to my untrained eyes, unless I’m doing it wrong.

I’m not totally sold on what my next scope will be; I like the idea of a Cassegrain because they’re relatively transportable and provide some technical advantages, such as the possibility of getting into astrophotography. Ideally, of course, I would like both a big Mak or Schmidt AND a big Dob. However, first I have to win the lottery.

I may have to wait for better weather for better seeing, unfortunately, as the weather has been unremittingly terrible for three months here. So I’ll wait until then before going out and spending a ton of money on equipment. Sadly, it’s right now that Jupiter is right up high in the sky and looking terrific.

9

Hi RickJay,

Just some clarification. I’ve got only Dobs now, but only because they have just about the best primary mirrors that are available to the amateur right now. They give incredible views that are at times “Hubblesque”.

But…I’ve also owned a few Meades (LX200s and ETX) that were very good, and the GOTO accuracy on the LX200s were excellent. The problems with Meade (and other brand) SCTs, as I see them, is that quality control for mechanicals and optics is spotty at Meade, it takes a long time for a closed-tube SCT to cool down, the secondary size robs you of a bit of contrast, and they are VERY sensitive to precise collimation. I mean VERY sensitive. But, if they’re cooled down, and you’ve bought a “good one”, and it’s collimated spot-on, then you’re gonna get real good views with it. I was very happy with my 10" and 12" LX200s until I stumbled upon Starmaster dobs, and then I was ruined. :wink:

Also, Celestron makes nice SCTs as well - in particular, their 9.25" and 11" SCTs are well-regarded. They’re trying real hard now to get back into the ring with Meade in the marketplace after some business issues, and I expect good stuff from them.

Mr. Athena

10

::::waves hand at RickJay::::

What do you see when you aim it at Mars? We might need you on this thread:
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=154184
In the near future I hear Mars is going to be the closest to Earth in roughly 75,000 years. I think that’s happening later this year.