Pluto occultation

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ChrisGreaves
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Pluto occultation

Post by ChrisGreaves »

To the best of my knowledge, this is the first time that the word occultation has been used in Eileen's Lounge.
Well, I have to be first at something.

Why the Australian Outback holds the key to the mysteries of Pluto is a 12-minute video full of indrawn-breath drama, but if you are in a hurry to see something that occurred three weeks ago, then fast-forward to the 11m0s mark.

The models showing the occultation used what looked like our Sol as the star, which tried to give me an initial impression that Pluto's orbit was inside that of Earth's orbit, whereas I have known since 1959 that Mister Venus Entered My Jolly Submarine Under the North Pole.
Cheers, Chris
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BobH
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Re: Pluto occultation

Post by BobH »

My dad (b. 1894) taught me this rhyme to learn the planets and their distance from the Sun:
Mercury, Venus, the Earth, Mars;
Jupiter, largest of the stars;
Saturn, Uranus, Neptune, too;
Far away and hard to view.

He must have been prescient in dismissing Pluto.
Bob's yer Uncle!
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ChrisGreaves
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Re: Pluto occultation

Post by ChrisGreaves »

BobH wrote:
23 Jun 2022, 18:25
He must have been prescient in dismissing Pluto.
Either that or he went to school before 1930.
My dad was schooled (1920-1937) in books, readers, that were old at the turn of the century:-
"Ten and ten make twenty,
Apples are a plenty
'For you!' says Mister Henty
A very nice gent, he"


I have a copy of my Hall and Knight "Elementary Trigonometry"
20220623_170345.jpg
which we used in high-school 1961-63. Back in those days, ladders leaned against a wall at an angle of 30º.
No-one had a mobile crane with a hydraulic jib.

Nostalgically yours
Chris
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Graeme
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Re: Pluto occultation

Post by Graeme »

That is a great video, thanks Chris. I didn't know about the occultation. As Bob's Dad says, only Mercury and Venus orbit the Sun within Earth's orbit. Pluto is a trans Neptunian, Kuiper belt object. The video is about what happens when Pluto passes in front of a distant star as seen from Earth. If you measure the brightness of that star and the colour of it's light, then when Pluto passes in front of it you can determine aspects of the nature of Pluto including the constituents of it's atmosphere using spectroscopy. Exoplanet scientists are starting to do this to look for exoplanet atmospheric signs of life.

Regards

Graeme

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ChrisGreaves
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Re: Pluto occultation

Post by ChrisGreaves »

Graeme wrote:
23 Jun 2022, 19:51
... when Pluto passes in front of a distant star as seen from Earth.
It seems to me that by now there must be a vast data base of stars, each star with its predicted position in the sky, magnitude and so on.
Pluto's position is predictable.

I know that Pluto is small and stars are apparent pin-pricks, but given the astronomical numbers involved, occultations by Pluto ought to be as common as muck.
I saw that while "Katherine" was the nominated spot, the eleven astronomers were strung out in a line to improve the chances of an on-track sighting, but this practice ought to be available when any inhabited locality is chosen.

I am, in short, surprised that this occultation was an "event"; I would have thought that Pluto must occultate a visible star at least once a week.
Cheers, Chris
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Graeme
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Re: Pluto occultation

Post by Graeme »

ChrisGreaves wrote:
24 Jun 2022, 06:49
I know that Pluto is small and stars are apparent pin-pricks, but given the astronomical numbers involved, occultations by Pluto ought to be as common as muck.

This is a similar question to Olbers paradox!

I'm not sure what magnitude they need to do the spectroscopy but Pluto has an apparent magnitude of 14.32. I have Stellerium set to include stars down to magnitude 14 because that's about what my telescope can see.

Screenshot 2022-06-25 082032.png

Occultations are surprisingly rare.
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ChrisGreaves
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Re: Pluto occultation

Post by ChrisGreaves »

Graeme wrote:
25 Jun 2022, 07:37
This is a similar question to Olbers paradox!
Graeme, What an interesting link1 Edgar Allan Poe, eh? His name cropped up, I think, somewhere in Mark Twain's autobiography, but I dursn't set aside the time to read/listen to it a fourth time.
I'm not sure what magnitude they need to do the spectroscopy but Pluto has an apparent magnitude of 14.32. I have Stellerium set to include stars down to magnitude 14 because that's about what my telescope can see.
Ahhah! So in layman's terms it boils down to needing a star of a specific apparent size, not wider, not narrower.
I see that now.
An apparently large star would give a view somewhat like the transit of Mercury, whereas a small star would be blotted out by Pluto.
That said, the database/catalogue of stars must be searchable for stars of 14.32 magnitude so that events like the one documented at Katherine can be scheduled.

I could not find the occultation setting in Stellerium , so my guess is that you have the Plus version.
Given my sky conditions (fog again at 3am), it would be handy to be able to filter out all but the brightest stars as a means of a gradual educational slope into recognizing stars.
Cheers, Chris
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