Mars is a dot on my 10" dobson?

[LuminousCRO]

I've put a 10mm Plossl eyepiece on a 10" dobson and Mars looks like a small circle. Even on my friends 3" reflector you can see ice capes. I am going to Austria to ski, so no hurry with answers.

10q in advance!☺

[brantuk]

Put your scope, eyepiece, and target info in here and it'll show what you should see in the fov:

http://www.12dstring.me.uk/fovcalc.php

You can play around with different scopes, eyepieces, cameras even and work out what you can expect to see or image. A 10mm eyepiece in a 250px just shows mars as a dot.

[John]

Mars is moving rapily away from us now. At it's closest, back in July, a small scope could show some details on the disk but now the disk has shrunk to less that 1/3rd of the size that it was in June - at 7.7 arc seconds it will appear as just a small pink spot at 120x (the magnification that your 10mm eyepiece gives with your scope) and even max power (around 250x on a night of good seeing) will not show much more.

The next opposition (when Mars is well placed to observe) will be October 2020.

Fortunately a 10 inch dobsonian is a very capable all round scope and there are many wonderful sights to keep you occupied until 2020 comes around

[Louis D]

17 minutes ago, LuminousCRO said:

Even on my friends 3" reflector you can see ice capes.

Was it this last week that 3" reflector showed ice caps or did it show them 5 months ago at opposition when it was much closer?  I have a 3" ED refractor, and Mars showed as little more than an orange-red dot recently.  Even in my 8" Dob, it shows as just a slightly bigger dot less than 1/3 the diameter it was in the summer.  I sometimes convince myself I can see slight shadings which might or might not really exist.  To see any significant detail visually at this time will require a very large and well figured mirror, a semi-tropical to tropical viewing site to elevate it out of the horizon murk, and steady seeing.

[LuminousCRO]

I know that this summer Mars was at it's closest in (maby I am wrong) 400 yrs. so that is a factor to include, but the seller told me I don't need anything else than this 10mm eyepiece. My uncle bought a 2x Barlow today so that should probably help.

[John]

1 minute ago, LuminousCRO said:

I know that this summer Mars was at it's closest in (maby I am wrong) 400 yrs. so that is a factor to include, but the seller told me I don't need anything else than this 10mm eyepiece. My uncle bought a 2x Barlow today so that should probably help.

It was the best approach of Mars for a long time but the 2020 one will be almost as good and, from the UK at least, Mars will be higher in the sky, which will help get better views. There was also a planet wide dust storm (on Mars !) this Summer which obscured a lot of the detail so we can hope that we don't see a repeat of that in 2020.

Using the barlow lens with the 10mm eyepiece will show you a slightly larger pink dot but the current angular size of Mars in the sky is very small so it's still going to be tough to see any details.

[Les Ewan]

Agreed,I took a look at Mars on Christmas Eve with my 300mm Newt and a good quality 10mm eyepiece giving a power of 150X and didn't see much more than a slightly gibbous disc between intervals of blobyness. With Mars so far away now only the best seeing will show  any details at all, if seeing is bad doubling magnification with a barlow will only make a bad situation worse.

[Space Hopper]

5 hours ago, LuminousCRO said:

I know that this summer Mars was at it's closest in (maby I am wrong) 400 yrs. 

15 years actually.

2003 was the closest Mars opposition we will see. Period.

2020s opposition won't be quite as close as this years perihelic opposition but it won't be that much further away either,

and more importantly, as John states, much, much better placed for us, close to Uranus in Pisces / Aries i believe.

[davejlec]

Try an off axis aperture mask made from cardboard  if the full aperture isn't cooperating when planets are not far above the horizon. Use a large enough circular piece that completely covers the front end of the tube- a long strip of cardboard taped to this acts as a rim and fits over the end of the tube.  Cut out a 3-1/2" to 4" circle that is off axis from center and in between the spider vanes- you don't want to see the vanes or the secondary when looking through the focus tube , if you do, you've cut the aperture too large.  

[JOC]

See page 1 here:

 

[Andy R]

On 27/12/2018 at 15:22, brantuk said:

Put your scope, eyepiece, and target info in here and it'll show what you should see in the fov:

http://www.12dstring.me.uk/fovcalc.php

You can play around with different scopes, eyepieces, cameras even and work out what you can expect to see or image. A 10mm eyepiece in a 250px just shows mars as a dot.

Added to my favourites. Fantastic link found it very useful (for a complete novice) especially if and when I choose another scope.

[cletrac1922]

Was out couple of nights ago, doing a presentation for local cub group

Viewed Mars through my 10" dob, and not the view had back in July

Was using a 17mm eyepiece, as gives better eye relief for eyes of 7-9yo's

When dropped 2 X barlow in, with yellow filter, could make out the icecaps

What sort of atmospheric conditions were you viewing under

If have almost invisible high level cloud, can also reduce clarity of what you are viewing

John

[MaHa]

On 27/12/2018 at 15:26, John said:

Mars is moving rapily away from us now. At it's closest, back in July, a small scope could show some details on the disk but now the disk has shrunk to less that 1/3rd of the size that it was in June - at 7.7 arc seconds it will appear as just a small pink spot at 120x (the magnification that your 10mm eyepiece gives with your scope) and even max power (around 250x on a night of good seeing) will not show much more.

The next opposition (when Mars is well placed to observe) will be October 2020.

Fortunately a 10 inch dobsonian is a very capable all round scope and there are many wonderful sights to keep you occupied until 2020 comes around

Thanks for some good information there, John. 

Mark. 

 

[John]

16 minutes ago, cletrac1922 said:

Was out couple of nights ago, doing a presentation for local cub group

Viewed Mars through my 10" dob, and not the view had back in July

Was using a 17mm eyepiece, as gives better eye relief for eyes of 7-9yo's

When dropped 2 X barlow in, with yellow filter, could make out the icecaps

What sort of atmospheric conditions were you viewing under

If have almost invisible high level cloud, can also reduce clarity of what you are viewing

John

When I was in Australia in November Mars was practically overhead. Here it's been bumping along not far from the horizon so we are looking through a lot more atmosphere than you are down there plus during the winter there are heating plumes etc, etc.

Add the extensive dust storm to the above and despite it's large apparent diameter, the 2018 opposition had it's challenges to say the least !

 

[cletrac1922]

18 minutes ago, John said:

When I was in Australia in November Mars was practically overhead. Here it's been bumping along not far from the horizon so we are looking through a lot more atmosphere than you are down there plus during the winter there are heating plumes etc, etc.

Add the extensive dust storm to the above and despite it's large apparent diameter, the 2018 opposition had it's challenges to say the least !

 

 

John

Currently Mars is about 45 degrees above the western horizon, just after sunset

 

Last Friday morning, as leaving for work around 4-30am, had conjunction of Venus with the moon

Was just under quarter moon, and Jupiter was above Venus

All three, about 30 degrees above eastern horizon, and sun had not risen, and just a slight bit of twilight on the horizon

Did not work out properly, when tried to image with my mobile phone

Was not able to hold my hand steady enough, and moon turned out blurry

Which part of Oz did you visit

I am inland in the hinterland, up behind Movie World theme park, and have number od hills between me and the foreshore, which block 80% of light pollution from Goldcoast

John 

 

[SIDO]

26 minutes ago, John said:

"the 2018 opposition had it's challenges to say the least !"

 

 

I'm becoming more convinced Mars goes away every other year to prevent us northerners from the getting Mars Derangement Syndrome ?