Which way is up?

[elliot]

I'm hoping you can help me with what seems to be a really obvious problem. I've a Dobsonian and everything I read says that in a reflector like this, the view is upside down, with South as up and West as Left. However when comparing what I see with Sky Safari, I see West is left but apparently North is up.

Looking at Saturn and what I think is Titan last night in a 10" dob with an 8mm + 2x Barlow, I see this layout with the forward rings obviously lower than the planet and angled a few degrees to the left, and with the Titan(?) off to the left and down. As Saturn is near the horizon I'm looking in the eyepiece almost parallel to the horizon... 

 

If I change the settings in Sky Safari to flip the view both horizontally and vertically, so S is up and W is left, as I'm led to believe I should be seeing, it doesn't match with what I'm seeing.  The forward rings of Saturn are higher and Titan angled is left and up...

 

 

This screen shot from SkySafari, with North up, matches what I see perfectly:

 

 

 

Where am I going wrong?  Why is North up in my reflector when I'm told it should be south?

 

 

 

 

 

 

[MarsG76]

The secondary mirror acts as a disgonal, where basically it flips only one axis... in this case flips south to up but leaves east right and west is left. 

[ronin]

Have a good look at the moon tonight, fly off to visit MarsG76 in Aus and have another look at the moon.

It will be the other way up. So which way is "up" is dependant on where you are.

In Aus Orion is the otherway up, doing a sort of handstand, around the equator he is flying through the air a bit like superman.

[Ricochet]

A simple test would be to simply see which way an object appears to move when you move the telescope. If you centre an object and push the telescope up which way does the object move? If it moves to the bottom then the telescope is not up/down reversed, while if it moves to the top it is reversed. 

Once you have ascertained whether the telescope is reversed the next step will be to more closely examine what you are seeing. Perhaps it is an optical illusion which way up the rings are and what you are thinking is Titan is actually a nearby star. 

24 minutes ago, MarsG76 said:

The secondary mirror acts as a disgonal, where basically it flips only one axis... in this case flips south to up but leaves east right and west is left. 

This is not true and disproved by the test outlined above. 

[MarsG76]

15 minutes ago, ronin said:

Have a good look at the moon tonight, fly off to visit MarsG76 in Aus and have another look at the moon.

It will be the other way up. So which way is "up" is dependant on where you are.

In Aus Orion is the otherway up, doing a sort of handstand, around the equator he is flying through the air a bit like superman.

Being in both hemispheres, I can say that this is definitely true.. the moon and constellations are flipped... So much for flat earthers, huh.

 

[rockystar]

your Barlow isn't an erecting Barlow,,is it? That will flip it back the other way, but may not flip E-W back over.

[ollypenrice]

Watch the drift of the stars in the stationary scope. They drift from east to west.

Olly

[Dave In Vermont]

In software-programs such as Stellarium, you have the option to use different grids with their own sets of coordinates - such as equatorial, terrestrial, galactic, etc. Most of us use terrestrial, or equatorial. I switch-off between these two. Terrestrial seems to be the standard default setting. You can go knutz and use all of them!

My 2¢,

Dave

 

[Nyctimene]

2 hours ago, ollypenrice said:

Watch the drift of the stars in the stationary scope. They drift from east to west.

Point the dob, using a rather high magnification, at a bright star and bring it into the center of the field of view.  Where the star exits the field of view, there's West. In a Newtonian scope, North is located 90° counterclockwise to the West (assumed that no other optical elements than eyepiece, filter and Barlow (non-erecting) are used). In SkySafari you have to switch to flip "both" , as you mentioned already above.

Perhaps you took a background star erroneously for Titan?

Hope this helps

Stephan

[elliot]

3 hours ago, rockystar said:

your Barlow isn't an erecting Barlow,,is it? That will flip it back the other way, but may not flip E-W back over.

no, not that I know of.

 

4 hours ago, Ricochet said:

Perhaps it is an optical illusion which way up the rings are and what you are thinking is Titan is actually a nearby star. 

This could definitely be true. All I can think of is that I was mistaken on the aspect of the rings.  Will try again when it's next clear which will be in about 3 months at this rate.

[Moonshane]

As above, let a star drift out of field. Where it hits the field stop, that's west. Opposite is east of course. http://articles.adsabs.harvard.edu//full/1907PA.....15...22W/0000023.000.html and the following page or two are old but give good advice I think. N is basically 90 degrees clockwise from East when using a non reversed system (like a newt which is basically just upside down but not reversed) and 90 degrees anticlockwise from East when using an E/W reversed system like a frac or SCT with a diagonal. So basically establish East and you'll know in your case that North is 90 degrees clockwise. So in other words 'down' not up in the screen shots given.

[Ricochet]

5 hours ago, elliot said:

no, not that I know of.

 

This could definitely be true. All I can think of is that I was mistaken on the aspect of the rings.  Will try again when it's next clear which will be in about 3 months at this rate.

I had some clear sky tonight and can confirm that in my dob Saturn appears as Sky Safari shows with the near side of the rings "up".

[Geoff Lister]

A couple of weekends ago I was looking at yachts on the Exe, with (1) 15x70 binoculars and (2) a 90mm Mak with star diagonal. With both, the masts were sticking up (good), but with the Mak, their names were backwards (not so good).

[SonnyE]

We always tell the kids that when underwater, follow the bubbles.

The bubbles always know which way is up.... 

 

What we need to learn is that Up, Down, Left or Right are just for our relating.

In space, there is no North, South, East, or West. So I've grown to simply relate which way an object will move when doing my alignments.

Sometimes an arrow moves the object one direction when, say West, of the N-S meridian. And that same arrow will move another object the opposite way when, say East, of the N-S Meridian.

I found it was confusing to try and think N-S-E-W in relation to the skies. That's good for Terra forma, but gets hard to relate when peering at the stars.

But then, I'm a refractor nut. Galileon in fact. So everything is bass-ackwards and upside down... 

Thank goodness stars are round! 

[elliot]

OK, definitely a case of confirmation bias. Up is down and left is right. As expected.

[SonnyE]

On 8/8/2017 at 16:39, elliot said:

OK, definitely a case of confirmation bias. Up is down and left is right. As expected.

Quite right. I had one hell of a time until I let go of the N-S-E-W thing I was so use to.

When I decided that Up was going to move the object down, and down was going to move the object up, I was able to just worry about left or right, except when they decided to reverse.

Then, the arrow buttons became as clear as mud. Quite simple.  

[SonnyE]

Hey Elliot, it came to me while doing my alignment...

If you lay down on your back, with your head towards the north, and your feet South, the way the mount moves makes more sense. Might give it a go.

[Bigwings]

WHICH WAY IS UP.

I have sorted this during the light and cloudy nights....

Sit in the garden and pour several large glasses of whisky. The test is more accurate the more whisky is consumed.

When the cloud breaks and you see a star, the direction you have to force your very relaxed body in order to get to your feet is UP.

This test works well..now I just need to understand the resulting rotation....hic!

[fozzybear]

3 hours ago, Bigwings said:

several large glasses of whisky

then field rotation comes into play beware of that.....

[freiform]

On 6.8.2017 at 14:43, ronin said:

In Aus Orion is the otherway up, doing a sort of handstand, around the equator he is flying through the air a bit like superman.

Thank you for this nice picture ;).