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10-07-2020, 23:10   #1
Oneiric 3
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Comet NeoWise

This is fascinating and something to look out for over the coming weeks:



According to the narrator (who runs a great channel) the comet should be visible in the northern sky, and best viewed in the late evening or very early morning.
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11-07-2020, 07:20   #2
oriel36
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According to the narrator (who runs a great channel) the comet should be visible in the northern sky, and best viewed in the late evening or very early morning.
https://www.youtube.com/watch?v=4AEluR-CBu4

I had been watching that comet since it came into view of the C3 camera but unlike most other comets which dive into the central Sun, this one progressed out of range of the camera and eventually as a dawn appearance to the right of the Sun as it crossed the orbital plane of the Earth.

Now it is both a twilight and dawn appearance which means it is above the central Sun and this is rare for all near planets of the solar system inhabit a region close to the orbital plane of the Earth. It is why Venus and Mercury transition from a twilight to dawn appearance as they move from left to right of the Sun and between the Earth or from a dawn to twilight appearance as they move behind the Sun but never a dawn and twilight appearance simultaneously.

The first annual appearance of the brightest star Sirius to the right of the Sun or a dawn appearance after being lost to the glare of the central Sun for a number of weeks marked a meteorological event that was the flooding by the Nile of the Delta and gives us our modern calendar system -

"On account of the precession of the rising of Sirius by one day in the course of 4 years therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the New Year" Canopus Decree, 236 BC
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11-07-2020, 07:50   #3
M.T. Cranium
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I just posted some info in the astronomy forum, this link is included:

https://skyandtelescope.org/astronom...se-and-lemmon/

otherwise have a look over there for more info. I think Ireland is far enough north that you should be able to view it all night although it will tend to dip close to the northern horizon around 0100-0200h. Further south it sets and then rises again during the night as those observers have the great bulk of my cranium in the way (or is it something to do with the earth, looking into it).
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11-07-2020, 09:31   #4
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Thanks MT

It's very easy to spot, I went out just after 2am and the comet was clearly visible without binoculars, tail and all. It reminded me of the way Hale Bopp looked a few weeks after its peak.

Throw in Jupiter, Saturn, Mars, the Moon, a red Venus rising, a pass by the ISS and a stunning display of NLC, it really was a class night for astronomy nerds


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I just posted some info in the astronomy forum, this link is included:

https://skyandtelescope.org/astronom...se-and-lemmon/

otherwise have a look over there for more info. I think Ireland is far enough north that you should be able to view it all night although it will tend to dip close to the northern horizon around 0100-0200h. Further south it sets and then rises again during the night as those observers have the great bulk of my cranium in the way (or is it something to do with the earth, looking into it).
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11-07-2020, 09:45   #5
oriel36
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Thanks MT

Throw in Jupiter, Saturn, Mars, the Moon, a red Venus rising, a pass by the ISS and a stunning display of NLC, it really was a class night for astronomy nerds
Jupiter and Saturn provide a different perspective to Venus and Mercury as we look towards the outer solar system and the slower moving planets. We are overtaking Jupiter and Saturn at our closest points at the moment as they temporarily fall behind in view(retrograde motion) -

https://apod.nasa.gov/apod/ap011220.html

The comet disrupts the normal predictive nature of that side of astronomy and that is why it was always disconcerting to astronomers throughout history where predictable motions of the planets and moon were upset. It still does today as I see people try to put the comet in perspective.
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11-07-2020, 11:46   #6
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Noctilucent clouds and Neowise at Howth Harbour this morning (can see the comet above the tower). Image is a bit out of focus - may have a better one from the summit which I'll post some other time. Wasn't sure to post this in noctilucent clouds thread or here.

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11-07-2020, 14:06   #7
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Noctilucent clouds and Neowise at Howth Harbour this morning (can see the comet above the tower). Image is a bit out of focus - may have a better one from the summit which I'll post some other time. Wasn't sure to post this in noctilucent clouds thread or here.

Hi, great photo! Were you using a slow shutter speed here, the tail of the comet looks so visible!?
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11-07-2020, 18:04   #8
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Hi, great photo! Were you using a slow shutter speed here, the tail of the comet looks so visible!?
Yeah, settings were ISO-100, f/4.0 and 30" with manual focus for interest. No exposure compensation.

Thanks for the compliment.
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13-07-2020, 13:31   #9
oriel36
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https://theskylive.com/planetarium?o...6999185|fov|50

That is the view of the inner solar system and the position of the comet just outside the glare of the Sun where it is seen largely as a dawn appearance but due to its location above the Sun, it straddles a twilight and dawn appearance. The reason for this is because everything to the right side of the Sun is a dawn appearance while all observations to the left of the Sun is a twilight appearance.

https://www.youtube.com/watch?v=4AEluR-CBu4&t=7s

If weather enthusiasts wish to understand the dynamics behind the seasons, they are going to have to appreciate the change in position of the stars from left to right of the central/stationary Sun in response to the Earth's orbital motion. The North polar latitude is fixed in orientation to Polaris so, by logic, the North pole also turns parallel to the orbital plane as a function of the Earth's orbital motion. It is why there is a single day/night cycle at that location despite a daily rotational velocity of zero.

The location of the comet and its position to the orbital plane of the Earth and to the central Sun is part of the more expansive perspective of the present celestial spectacle, at least those open to interpretative judgments.
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13-07-2020, 14:02   #10
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Will this be still there in September when the sky in the Northwest will be free of cloud again.

Only 20hours of sunlight in July so hard to get a cloudless sky.
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13-07-2020, 14:39   #11
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Another more curious comet to look out for will show up on Friday 13th April 2029, viewable to 2bn with their naked eyes.

Named after the Egyptian god of 'chaos, ship or chaotic being': Apophis 99942
It'll be the closest of this size, to breeze by in 1,000yrs or so.

It stretches about 1,100 feet (340 meters) across and will pass within 19,000 miles (31,000 kilometers) of Earth's surface.
There is slight concern that the Earth's gravitational pull pull/distort Apophis, during this close approach.
Back in 2004 it was given a small chance 2.7% of an Earth slam, since reduced.

If this risk does increase for some reason, and Trump's new space force seeks to blast it (like the movies),
this will only worsen the risk (more debris risk/scatter, contained within it's own large gravitational pull).
The potential damage from something this size, would be fitting with that known as 'Wormwood'.
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13-07-2020, 15:04   #12
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Will this be still there in September when the sky in the Northwest will be free of cloud again.

Only 20hours of sunlight in July so hard to get a cloudless sky.
https://theskylive.com/planetarium?o...5777265|fov|56

I adjusted the view to show the comet roughly in relation to orbital plane of the Earth by using Venus and Mercury as a guide for roughly similar orbital planes to the Earth with the central Sun stationary to all our motions. There is a hands-on app which allows observers to work with the perspective that bests suits them especially from a solar system perspective rather than being restricted to the local horizon and daily rotational coordinates of North/South/East/West.

https://ssd.jpl.nasa.gov/sbdb.cgi?ss...=0;log=0;cad=0

It gives a lot of depth perception which should attract the curious by grabbing the central image and arranging it until it satisfies the trajectory of the comet in relation to the motions of the planets by scrolling the dates forwards or backwards.

Everything to the right of the Sun is a dawn appearance while everything the left of the Sun is a twilight appearance so the trajectory of Neowise is towards an evening appearance quite shortly but moving away from the Sun which will therefore eventually diminish the luminosity of the tail. It should be good enough for July but as seen in the C3 camera, it moves pretty rapidly from its position from below to above the Sun a few weeks ago to presently traveling from above the Sun to below the Sun's equatorial plane in the coming weeks in the same rapid motion

https://www.youtube.com/watch?v=4AEluR-CBu4&t=7s

While the narrator of the time lapse picks up on the now familiar change in positions of the background stars and Mercury as it passes between the Earth and the Sun, there is another important event within that sequence. He mentions U Orionus as the comet heads Northwards with this star changing position to the orbital plane in response to the Earth's orbital motion. The comet too is subject to this apparent change from left to right of the stationary Sun but that is also a perspective created by the Earth's own orbital motion.

The point here is that the great star Sirius too is transitioning from an evening to morning appearance or from left to right of the Sun. It was the first annual appearance at dawn which represents the foundations of all timekeeping, at least in our modern era -

"On account of the precession of the rising of Sirius by one day in the course of 4 years therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the New Year" Canopus Decree, 236 BC

That observation is probably far older than that written expression -

https://arxiv.org/ftp/arxiv/papers/1509/1509.00134.pdf


The comet is a great way for people to consider how our ancestors made use of twilight and dawn appearances and how it finds an expression in heliocentric astronomy and especially cause and effect between the motions of our planet and Earth sciences including meteorology.

Last edited by oriel36; 13-07-2020 at 20:22.
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13-07-2020, 21:45   #13
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Originally Posted by Accumulator View Post
Another more curious comet to look out for will show up on Friday 13th April 2029, viewable to 2bn with their naked eyes.

Named after the Egyptian god of 'chaos, ship or chaotic being': Apophis 99942
It'll be the closest of this size, to breeze by in 1,000yrs or so.

It stretches about 1,100 feet (340 meters) across and will pass within 19,000 miles (31,000 kilometers) of Earth's surface.
There is slight concern that the Earth's gravitational pull pull/distort Apophis, during this close approach.
Back in 2004 it was given a small chance 2.7% of an Earth slam, since reduced.

If this risk does increase for some reason, and Trump's new space force seeks to blast it (like the movies),
this will only worsen the risk (more debris risk/scatter, contained within it's own large gravitational pull).
The potential damage from something this size, would be fitting with that known as 'Wormwood'.
It will be raining that year
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13-07-2020, 22:04   #14
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It will be raining that year
Ah sure 'Lord of chaos' might burn up any cloud in these parts, at it's closest approach, just before 6 p.m. EDT Fri 13th Apr 2029, Apophis will be over the Atlantic Ocean – and it will move so fast that it will cross the Atlantic in just an hour (West Africa to NE Americas).

It will also cross the width of a typical visable full moon within 60seconds.

It won't be earth destroying should it touch down, but would be double the object size of the 1908 Tunguska event (possibly more than double the impact too, depending on economies of scale and angle of approach (e.g. 45 degree).

Could certainly kick up enough dust for Wormwood's 3days of darkness or throw in a (super-mega) tsunami for the Atlantic, and the 1/4 world population reduction might also be on the cards.

Something of this size is due to slam every 80k yrs or so.

Expect some Sat interference from this badboy (blue dots).



If Musk is having a raffle for free trips to colonise Mars, have a lucky dip.
If you have a full 7mm wetsuit, and head torch, also have that accessible, that afternoon.
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14-07-2020, 10:05   #15
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Ah sure 'Lord of chaos' might burn up any cloud in these parts, at it's closest approach, just before 6 p.m. EDT Fri 13th Apr 2029, Apophis will be over the Atlantic Ocean – and it will move so fast that it will cross the Atlantic in just an hour (West Africa to NE Americas).

It will also cross the width of a typical visable full moon within 60seconds.

It won't be earth destroying should it touch down, but would be double the object size of the 1908 Tunguska event (possibly more than double the impact too, depending on economies of scale and angle of approach (e.g. 45 degree).

Could certainly kick up enough dust for Wormwood's 3days of darkness or throw in a (super-mega) tsunami for the Atlantic, and the 1/4 world population reduction might also be on the cards.

Something of this size is due to slam every 80k yrs or so.

Expect some Sat interference from this badboy (blue dots).



If Musk is having a raffle for free trips to colonise Mars, have a lucky dip.
If you have a full 7mm wetsuit, and head torch, also have that accessible, that afternoon.
Im up a mountain, I'll be, grand...
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