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Old 20-07-2018, 09:25 PM
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OzEclipse (Joe Cali)
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Next Saturday's unprecedented lunar eclipse is no cause for alarm

Just 7 or 8 sleeps to go until next Saturday morning's twilight lunar eclipse.

I've prepared a short mostly graphical summary on my website :
http://joe-cali.com/eclipses/PLANNIN...728/index.html

Joe
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Old 21-07-2018, 12:56 AM
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Mauritius or Reunion, there the totally eclipsed Moon (with Mars) is in the zenith !
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Old 22-07-2018, 05:03 AM
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How is it that I am not surprised?
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Old 22-07-2018, 02:58 PM
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I'm trying to work out whether to observe from my back yard or travel. The first is easier of course but the western horizon is partially obstructed. The question is: how low will the moon be when it disappears into the twilight? From Joe's diagram it appears it could be as low as 5 degrees. Anyone have any idea? [I have seen a rising eclipse but that was over the ocean and I have no memory of how high it was when we first spotted it.]
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Old 22-07-2018, 03:29 PM
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According to Starry Night Pro this is the situation for Wollongong at 5:15am, 18 degrees (first image), 5:45am, 13 degrees (second image) and 6:15am, 7 degrees (third image).
PS: My balcony faces east, so I will have to go downstairs and find a spot with my small telescope and my camera. Hopefully nobody will try to steal my scope.
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Last edited by OzStarGazer; 22-07-2018 at 03:42 PM.
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Old 22-07-2018, 04:13 PM
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Anyone planning anything in Adelaide?

Im thinking of going up to the Mt Lofty summit, it has a great view over the city and also east over the water.

Either that or there are some nice spots along the coast.
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Old 22-07-2018, 07:50 PM
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Quote:
Originally Posted by AstralTraveller View Post
I'm trying to work out whether to observe from my back yard or travel. The first is easier of course but the western horizon is partially obstructed. The question is: how low will the moon be when it disappears into the twilight? From Joe's diagram it appears it could be as low as 5 degrees. Anyone have any idea? [I have seen a rising eclipse but that was over the ocean and I have no memory of how high it was when we first spotted it.]
David

It depends on local aerosols and other particulates in the air that might increase(by scatter) or decrease(by absorption) the brightness of the sky and contribute to extinction of the Moon. The moon will darken to midtotality then brighten to the end of totality at sunrise.

I'd suggest it isn't really possible to predict.

Once twilight arrives and sky brightness starts being comparable to the moon, all you need to do is switch your camera to Av mode and let it happen.
Even if the moon disappears, keep shooting, it might reappear as the Moon brightens.

Joe
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Old 23-07-2018, 04:28 AM
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I will watch the first part online and go down to find a spot short before 5...
There won't be another total eclipse so soon, so hopefully I will get a glimpse of it.
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Old 23-07-2018, 07:02 AM
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Graze during Eclipse totality

The moon's northern limb will graze by SAO 163510 during totality. The star is mag. 7.9 (7.3 Red). Map of the northern limit line attached below.

I'm not sure of the observability of the star against the Umbra but I'll find out...
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Old 23-07-2018, 11:33 AM
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Latest weather forecast around here:
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  #11  
Old 23-07-2018, 06:20 PM
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OzEclipse (Joe Cali)
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Quote:
Originally Posted by DaveGee View Post
The moon's northern limb will graze by SAO 163510 during totality. The star is mag. 7.9 (7.3 Red). Map of the northern limit line attached below.

I'm not sure of the observability of the star against the Umbra but I'll find out...
Dave,

I think the graze you are referring to in eastern AU occurs at about 6am -
  • 30 mins into totality,
  • Moon altitude 12 degrees
  • 1 hr until moonset
  • 4 mins before the start of nautical twilight ACT, maybe about 10 mins after the start of nautical twilight on the coast.
Background sky brightness, atmospheric instability, low altitude extinction not to mention the rain that's predicted along the graze path, will further complicate observations. It passes 10k from my dark sky site but I don't think it's a goer. I'll probably stay in Canberra.

cheers

Joe
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Old 23-07-2018, 10:51 PM
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Forget the graze if you live in Sydney/Brisbane/Melbourne/Hobart.

In Sydney the moon is fully eclipsed (U2) at 5:30 am but sunrise is at 6:51 am. With the graze at 6 am that means the sky will be quite bright, so the moon will have vanished and be invisible. You can forget mag 7 stars even in a scope - I tried yesterday.

It might be feasible in Adelaide (and only maybe) but its reasonable for observers in Perth.

Its a pity because its a very very long wait for the good next total lunar eclipse over Australia - in 2031.
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Old 23-07-2018, 11:01 PM
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What is unprecedented about this eclipse?
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Old 24-07-2018, 12:09 AM
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joe was having a jibe at a certain tv network whose collective memory is barely 3 weeks. Even rain was “unprecedented”...

Cripes Morton, you don’t watch much tv...
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Old 24-07-2018, 12:04 PM
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Originally Posted by MortonH http://www.iceinspace.com.au/vbiis/i...s/viewpost.gif
What is unprecedented about this eclipse?


Lunar eclipse of the century

A total lunar eclipse is always an awe-inspiring sight, but this one is special:
  • It's the longest lunar eclipse of the 21st century. The Moon will travel through the very center of Earth's shadow, and the distance from Earth to the Moon and to the Sun will be unusually large—making this eclipse the longest you will likely see in your lifetime!
  • It will coincide with the Perseids meteor shower, so you might see a few shooting stars during totality.
  • Mars will be at its brightest. The planet will appear as a reddish star, quite close to the Moon.
Source: https://www.timeanddate.com/live/



Then again, the tetrad was also supposed to be unique.


I do like the idea that it lasts longer than usual because clouds can be pretty nasty so the longer it lasts the better the chances to get a glimpse of it.
If the weather cooperates it would be the very first eclipse I can see since I got into astronomy.

Last edited by OzStarGazer; 24-07-2018 at 12:16 PM.
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Old 24-07-2018, 12:08 PM
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... although unfortunately I won't see it all from where I am because it will be too bright towards the end and there are obstructions in the west (the escarpment).
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Old 24-07-2018, 01:25 PM
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Quote:
Originally Posted by Wavytone View Post
joe was having a jibe at a certain tv network whose collective memory is barely 3 weeks. Even rain was “unprecedented”...

Cripes Morton, you don’t watch much tv...

Question: if a network is soooo 'bad' (insert fruity term here) that they cannot remember three weeks ago why would anyone who considers themselves educated, reasonable or possessed of good taste watch said station? Isn't knowing anything about that station a form of confession? "Forgive me Father for I know what the channel 10 weather girl wore last night."
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Old 24-07-2018, 01:28 PM
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... although unfortunately I won't see it all from where I am because it will be too bright towards the end and there are obstructions in the west (the escarpment).

From your place the elevation of the escarpment is <5 degrees. (It's about 5 from my place in Tarrawanna.) So I expect the dawn will get you before the escarpment.
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Old 24-07-2018, 06:12 PM
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OzEclipse (Joe Cali)
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Quote:
Originally Posted by MortonH View Post
What is unprecedented about this eclipse?
Just a bit of fun. It's a play on a line from an old 1980's song by Queen, "Flash"
Original line in the song was, "Today's unprecedented solar eclipse is no cause for alarm."

Joe
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Old 24-07-2018, 09:00 PM
Wavytone (Nick)
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A CHALLENGE FOR VISUAL TYPES: Here is a technicality about this eclipse which might interest a visual observer:

It is possible to briefly see simultaneously both the rising sun in the east, AND the eclipsed moon setting in the west, thanks to atmospheric refraction.

However this is only possible if you happen to be standing on a decent site with really PERFECT low horizons east and west (and I do mean zero degrees altitude) AND very clear air. In other words: if you live in Sydney fuggedaboutit.

I saw this once with a similar lunar eclipse in the late 1970's at Mt Stromlo, where the sun rose in the east with the moon setting during the total phase (after second contact).

I've seen three similar lunar eclipses before - one in the early 1980's where at sunset the moon rose fully eclipsed, and two where the moon set soon after the total phase began. In all three cases it was a total waste of time setting up a scope and I won't be getting out of bed for this one.

Yes its the longest this century but in the eastern states disappointing. The time of second contact (5:30) is well into twilight so the moon will basically disappear and won't be much of a sight. To see it properly you have to be much further west - Perth, for example.

The unfortunate part - for the beginners here - is that it is going to be a very unusually long wait for another one over the eastern states - 2031 !

Aside: Something worthy of "Have You Been Paying Attention" (yes I do watch it) ... the ABC was guilty of calling the recent bushfire at Tathra "unprecedented" and was quickly chastised in letters to the editor of the SMH and Herald Sun for rather sloppy journalism - if the ABC had bothered to check the RFS website they would have found no less than 11 recent precedents dwarfing the Tathra fire. The ABC's sloppiness also rated a brief mention on 7 and 9.

Last edited by Wavytone; 24-07-2018 at 10:54 PM.
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