Planets on Parade and a Southern Hemisphere Mars Extravaganza

[Nic in Western NYS]

https://www.skyandtelescope.com/observing/astronomy-podcast-july-2018/

Northern hemisphere evening right after sunset:  Mercury makes a brief appearance, Venus is WOW, Jupiter is regal, and Saturn is also right up there ready to be viewed.  Uranus and Neptune are also visible (Pluto too but you need a BIG scope).

If you're up really early or late (like 3-4 am) you'll get a once every few decades look at Mars.  It is going to be at close to its closest to Earth later this month.  It is already almost as bright as Jupiter.  It's VERY far south in the skies so this is a perfect time for our Aussie and NZ friends to get a best in lifetime view of the Red Planet later this month.  Go to an observatory that has a big old scope with public viewing times (too bad there's a dust storm on Mars now so the view is somewhat hazy).

I just got a new telescope with fancy doo-dads so I'm a bit pumped.

Cheers!

Oh, the ST is running super too. 

[Guzzi Gal]

I know what the kids and I will be doing this evening!

https://www.timeanddate.com/astronomy/night/usa/phoenix

[balvenie]

Thank you Nic

[Nic in Western NYS]

Thank you Nic

I bet Mars looks amazing in front of the southern Milky Way. For us mid-northern latitude types, it's about as far south as it possibly could get, meaning poor seeing and limited hours of visibility but for you in Oz it's both wicked close to Earth at only .39AU (39% of the distance from the Earth to the Sun.) AND close to zenith.   Enjoy!

[guzzisteve]

There is a bright one in the western sky every night, it disappears to the NW. I used to watch them at dawn, the last stars to show brightness are the planets. 

[Nic in Western NYS]

There is a bright one in the western sky every night, it disappears to the NW. I used to watch them at dawn, the last stars to show brightness are the planets.

Venus it is - brightest celestial object except for the sun and moon

[kingoffleece]

I've been out the past few nights taking it all in.  fantastic show.

[Huzo]

My home town is 37 deg South 143 deg East.
Bottom right hand corner of Australia. That bright orange light overhead at midnight...
Is that Mars..?

[JamesNFalconaut]

Is that Mars..?
Yes.  Rises around 1800, and for the first hr or so looks pretty orange and big

[Nic in Western NYS]

My home town is 37 deg South 143 deg East.
Bottom right hand corner of Australia. That bright orange light overhead at midnight...
Is that Mars..?

That's him.

[Nic in Western NYS]

Is that Mars..?
Yes.  Rises around 1800, and for the first hr or so looks pretty orange and big

Evening-before-last here was pretty hot and hazy.  At about 2200 (we're at about 43N latitude) to my west Venus was close to the horizon and a bright orange. To my southeast, Mars was bright FIRE RED as it rose in the late twilight.  Usually Venus would be a bit yellow and Mars orange.  An optical illusion is that it looked big - the brain routinely mixes up bright with big.  You can't see the disk (rather than it being a point) without optical aid. Cheers!

[JamesNFalconaut]

Yes "looks big" as in appears big.
Incidentally Nic, what's the explanation for the moon, which is not as bright when it rises as later when it's higher, but looks bigger as it rises and sets?
They used to say it was the atmosphere til someone worked out that should make it smaller.

[Nic in Western NYS]

Yes "looks big" as in appears big.
Incidentally Nic, what's the explanation for the moon, which is not as bright when it rises as later when it's higher, but looks bigger as it rises and sets?
They used to say it was the atmosphere til someone worked out that should make it smaller.

The optical illusion with the moon that I've heard most is that it appears larger when it rises and sets.  My understanding is that it has to do with its apparent proximity to ground objects.   The actual angle subtended by the moon stays about the same - it's 1/4 of the width of your forefinger held at arm's length (0.5 degree, finger takes up about 2 degrees).  Same with the sun - same apparent size. 

[Lannis]

Another neat thing is that even with a good pair of 7x50 binoculars, you can see Venus as a crescent.   It's brightest when it's a crescent, like a tiny moon ....

Lannis

[Huzo]

The optical illusion with the moon that I've heard most is that it appears larger when it rises and sets.  My understanding is that it has to do with its apparent proximity to ground objects.   The actual angle subtended by the moon stays about the same - it's 1/4 of the width of your forefinger held at arm's length (0.5 degree, finger takes up about 2 degrees).  Same with the sun - same apparent size.

I love this one.
I have not done it yet. But I want to make a gauge with two pointers about half a metre long.
Looking through a peep hole, (reminds me of Vegas..), you could adjust the pointers to show the exact size of the moon, and compare it with later when overhead.
There's gotta be a difference.

[Lannis]

I love this one.
I have not done it yet. But I want to make a gauge with two pointers about half a metre long.
Looking through a peep hole, (reminds me of Vegas..), you could adjust the pointers to show the exact size of the moon, and compare it with later when overhead.
There's gotta be a difference.

Nope.  It's a great optical illusion.   Your experiment will confirm it ....

Lannis

[Nic in Western NYS]

I love this one.
I have not done it yet. But I want to make a gauge with two pointers about half a metre long.
Looking through a peep hole, (reminds me of Vegas..), you could adjust the pointers to show the exact size of the moon, and compare it with later when overhead.
There's gotta be a difference.

Wild eh?  Look at pictures of the total solar eclipse - it's right there.  We're the only planet in the solar system whose moon JUST BARELY covers the disk of the sun during eclipse showing the corona or outer atmosphere of the sun.  Just wild stuff.

[Huzo]

Wild eh?  Look at pictures of the total solar eclipse - it's right there.  We're the only planet in the solar system whose moon JUST BARELY covers the disk of the sun during eclipse showing the corona or outer atmosphere of the sun.  Just wild stuff.

Yeah, the Sun's 400 times the diameter of the moon and 400 times further away so when viewed from the side, the rule of similar triangles, has that phenomenon covered.
However..
Anybody who tells me that the moon does not look bigger on some nights just as it crests the horizon looking like a spherical, yellow, internally illuminated, hot air balloon, compared to the white golf ball overhead later on, will need to bring something more to the table than...
"Sorry mate you're wrong 'cos I bloody well said so..."
The big problem I have is that, everybody who tells me I'm wrong is more educated and probably more intelligent than I am...
That's gunna put a spanner in my works, I can just feel it.

[Nic in Western NYS]

Yeah, the Sun's 400 times the diameter of the moon and 400 times further away so when viewed from the side, the rule of similar triangles, has that phenomenon covered.
However..
Anybody who tells me that the moon does not look bigger on some nights just as it crests the horizon looking like a spherical, yellow, internally illuminated, hot air balloon, compared to the white golf ball overhead later on, will need to bring something more to the table than...
"Sorry mate you're wrong 'cos I bloody well said so..."
The big problem I have is that, everybody who tells me I'm wrong is more educated and probably more intelligent than I am...
That's gunna put a spanner in my works, I can just feel it.

Hey mate.  I'm not the dag to tell you you're wrong because you're not wrong, it does seem bigger.  "Seem" and "is" though aren't quite the same.  https://news.nationalgeographic.com/2016/12/moon-illusion-explained-horizon-size-supermoon-space-science/
Cheers!

[JamesNFalconaut]

Good link Nic.  Cold and clear here in Melbourne tonight.  Mars enormous around 1930.
This made sense to me:
"One reason why the horizon might appear more distant than the sky overhead is that our brains perceive the shape of “space” as a gently flattened dome rather than a perfectly round sphere. That means we judge celestial objects that are overhead to be closer than celestial objects on the horizon"
But it's not completely satisfying.  The moon is bigger I tells ya.  Actually they do say it's shrunk 90m in the last 4.5 Billion years.
I suspect Father Ted has good handle on it....though Dougal doesn't:
https://www.youtube.com/watch?v=OXypyrutq_M

[Lannis]

Anybody who tells me that the moon does not look bigger on some nights just as it crests the horizon looking like a spherical, yellow, internally illuminated, hot air balloon, compared to the white golf ball overhead later on, will need to bring something more to the table than...

It absolutely DOES LOOK bigger to your eye.   But if you measure the angle that it actually subtends in the sky (as you proposed) you'll see that it is NOT bigger.    There's no way for it to ACTUALLY be bigger.   What did it do, move 40,000 miles closer to the earth between 9 PM and midnight?

You've seen optical illusions before; if not, just google "optical illusion images" and you'll see ones that you won't believe; lines that you SWEAR could not be parallel until you lay a ruler on them, boxes where you'd bet your life that box "A" is WAY bigger than box "B" until you actually measure them ... The moon near the horizon versus the moon overhead is exactly the same phenomenon ....

Lannis

[Huzo]

It absolutely DOES LOOK bigger to your eye.   But if you measure the angle that it actually subtends in the sky (as you proposed) you'll see that it is NOT bigger.    There's no way for it to ACTUALLY be bigger.   What did it do, move 40,000 miles closer to the earth between 9 PM and midnight?

You've seen optical illusions before; if not, just google "optical illusion images" and you'll see ones that you won't believe; lines that you SWEAR could not be parallel until you lay a ruler on them, boxes where you'd bet your life that box "A" is WAY bigger than box "B" until you actually measure them ... The moon near the horizon versus the moon overhead is exactly the same phenomenon ....

Lannis

Yeah all fair comments.
I've never suggested that it IS bigger, but if you are adamant that the angle subtented is the same at moonrise and overhead, then I simply must stand educated.
I never ever would have said so though...

[Lannis]

Yeah all fair comments.
I've never suggested that it IS bigger, but if you are adamant that the angle subtented is the same at moonrise and overhead, then I simply must stand educated.
I never ever would have said so though...

If you don't want to build an angle-measuring quadrant, you can get a 2 or 3 foot long cardboard tube like gift-wrapping paper comes wrapped around.    Look at the moon through that when it's down near the horizon looking huge, and it will suddenly appear the same size as it does overhead ...

Not definitive or exact, but will demonstrate how much the apparent proximity to the ground affects what you see.

Lannis

[guzzisteve]

Wathing last night and bout 10:25 here comes the SpaceLab deal zooming across SW to NE. Cool Stuff.

SpaceLab fell already, Space Station.