APOD: Looking Sideways from the Parker... (2019 Dec 09)

Comments and questions about the APOD on the main view screen.
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APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by APOD Robot » Mon Dec 09, 2019 5:07 am

Image Looking Sideways from the Parker Solar Probe

Explanation: Everybody sees the Sun. Nobody's been there. Starting in 2018 though, NASA launched the robotic Parker Solar Probe (PSP) to investigate regions near to the Sun for the first time. The PSP's looping orbit brings it yet closer to the Sun each time around -- every few months. The featured time-lapse video shows the view looking sideways from behind PSP's Sun shield during its first approach to the Sun a year ago -- to about half the orbit of Mercury. The PSP's Wide Field Imager for Solar Probe (WISPR) cameras took the images over nine days, but they are digitally compressed here into about 14 seconds. The waving solar corona is visible on the far left, with stars, planets, and even the central band of our Milky Way Galaxy streaming by in the background as the PSP orbits the Sun. PSP has found the solar neighborhood to be surprisingly complex and to include switchbacks -- times when the Sun's magnetic field briefly reverses itself. The Sun is not only Earth's dominant energy source, its variable solar wind compresses Earth's atmosphere, triggers auroras, affects power grids, and can even damage orbiting communication satellites.

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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by alter-ego » Mon Dec 09, 2019 6:26 am

Pretty cool.
Jupiter, Saturn and Mercury are identifiable in the video by their changing positions. The fastest moving planet, visible at the end, is Mercury. The HPLN is congruent with (and likely defined as) elongation from the sun as viewed from the PSP. The 2nd close-approach (April 2019) video shows Mercury and Venus in that order, and there appear to be more well-separated corona "streamers".
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by orin stepanek » Mon Dec 09, 2019 1:07 pm

Impressive to see the stars and even the Milky Way pass by! Surprised these weren't bleached out of view from the brightness! 8-) :thumb_up:
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by Chris Peterson » Mon Dec 09, 2019 2:30 pm

orin stepanek wrote:
Mon Dec 09, 2019 1:07 pm
Impressive to see the stars and even the Milky Way pass by! Surprised these weren't bleached out of view from the brightness! 8-) :thumb_up:
Well, the streamers are all very dim... being close to the Sun doesn't change that. And there's no scattering atmosphere. So all you need is a shield to shadow the optics from the Sun itself (because that light would scatter in the camera and reduce the contrast) in order for the stars to show this way.
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by neufer » Mon Dec 09, 2019 2:40 pm

Chris Peterson wrote:
Mon Dec 09, 2019 2:30 pm
orin stepanek wrote:
Mon Dec 09, 2019 1:07 pm

Impressive to see the stars and even the Milky Way pass by! Surprised these weren't bleached out of view from the brightness! 8-) :thumb_up:
Well, the streamers are all very dim... being close to the Sun doesn't change that. And there's no scattering atmosphere. So all you need is a shield to shadow the optics from the Sun itself (because that light would scatter in the camera and reduce the contrast) in order for the stars to show this way.
  • I just knew there had to be a good reason to shield the optics from the Sun itself.
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by Chris Peterson » Mon Dec 09, 2019 2:45 pm

neufer wrote:
Mon Dec 09, 2019 2:40 pm
Chris Peterson wrote:
Mon Dec 09, 2019 2:30 pm
orin stepanek wrote:
Mon Dec 09, 2019 1:07 pm

Impressive to see the stars and even the Milky Way pass by! Surprised these weren't bleached out of view from the brightness! 8-) :thumb_up:
Well, the streamers are all very dim... being close to the Sun doesn't change that. And there's no scattering atmosphere. So all you need is a shield to shadow the optics from the Sun itself (because that light would scatter in the camera and reduce the contrast) in order for the stars to show this way.
  • I just knew there had to be a good reason to shield the optics from the Sun itself.
Of course, it's not just the optics. The shielding protects the entire probe from the heat and radiation that would otherwise damage or destroy it so close to the Sun.
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by joycedlync » Mon Dec 09, 2019 3:52 pm

What is the object in the middle of the picture about 3 seconds in? It sorta looks like Saturn with rings, or maybe a planet with a moon. Or maybe a satellite, although I'm sure it's way too big to be that.

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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by neufer » Mon Dec 09, 2019 4:46 pm

joycedlync wrote:
Mon Dec 09, 2019 3:52 pm

What is the object in the middle of the picture about 3 seconds in? It sorta looks like Saturn with rings, or maybe a planet with a moon. Or maybe a satellite, although I'm sure it's way too big to be that.
At a perihelion of 15,410,000 miles the Parker Probe was within Vulcan's orbit of 16,000,000 miles:
https://en.wikipedia.org/wiki/Vulcan_(hypothetical_planet) wrote:
<<Vulcan is a small hypothetical planet that was proposed to exist in an orbit between Mercury and the Sun. Attempting to explain peculiarities of Mercury's orbit, the 19th-century French mathematician Urbain Le Verrier hypothesized that they were the result of another planet, which he named "Vulcan".

A number of reputable investigators became involved in the search for Vulcan, and despite occasional claimed observations, no such planet was ever confirmed. Peculiarities in Mercury's orbit have now been explained by Albert Einstein's theory of general relativity. Searches of data gathered by NASA's two STEREO spacecraft have failed to find any vulcanoids that could have accounted for claimed observations of Vulcan. It is doubtful that there are any vulcanoids larger than 5.7 kilometres in diameter. There are a number of Mercury-crossing asteroids, but all have a semi-major axis larger than Mercury's.
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What's it all about, Alfvén?

Post by neufer » Mon Dec 09, 2019 5:41 pm

https://en.wikipedia.org/wiki/Parker_Solar_Probe#Findings wrote:
Click to play embedded YouTube video.
<<On December 4, 2019, the first four research papers were published describing findings during the Parker Solar Probe's first two dives near the Sun. They reported the direction and strength of the Sun's magnetic field, and described the unusually frequent and short-lived changes in the direction of the Sun's magnetic field. These measurements confirm the hypothesis that Alfvén waves are the leading candidates for understanding the mechanisms that underlie the coronal heating problem. The probe observed approximately a thousand "rogue" magnetic waves in the solar atmosphere that instantly increase solar winds by as much as 133 km/s and in some cases completely reverse the local magnetic field. They also reported that, using the "beam of electrons that stream along the magnetic field", they were able to observe that "the reversals in the Sun's magnetic field are often associated with localized enhancements in the radial component of the plasma velocity (the velocity in the direction away from the Sun's centre)". The researchers found a "surprisingly large azimuthal component of the plasma velocity (the velocity perpendicular to the radial direction). This component results from the force with which the Sun's rotation slingshots plasma out of the corona when the plasma is released from the coronal magnetic field".>>
Last edited by neufer on Tue Dec 10, 2019 5:02 pm, edited 1 time in total.
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Re: What's it all about, Alfvén?

Post by Ann » Mon Dec 09, 2019 7:25 pm

neufer wrote:
Mon Dec 09, 2019 5:41 pm
https://en.wikipedia.org/wiki/Parker_Solar_Probe#Findings wrote:
Click to play embedded YouTube video.
<<On December 4, 2019, the first four research papers were published describing findings during the Parker Solar Probe's first two dives near the Sun. They reported the direction and strength of the Sun's magnetic field, and described the unusually frequent and short-lived changes in the direction of the Sun's magnetic field. These measurements confirm the hypothesis that Alfvén waves are the leading candidates for understanding the mechanisms that underlie the coronal heating problem. The probe observed approximately a thousand "rogue" magnetic waves in the solar atmosphere that instantly increase solar winds by as much as 133 km/s and in some cases completely reverse the local magnetic field. They also reported that, using the "beam of electrons that stream along the magnetic field", they were able to observe that "the reversals in the Sun's magnetic field are often associated with localized enhancements in the radial component of the plasma velocity (the velocity in the direction away from the Sun's centre)". The researchers found a "surprisingly large azimuthal component of the plasma velocity (the velocity perpendicular to the radial direction). This component results from the force with which the Sun's rotation slingshots plasma out of the corona when the plasma is released from the coronal magnetic field".>>
Didn't understand too much of that (well, I did understand a bit, I think) but the main point to me is that the Sun is slingshotting plasma out of its corona. Yep, the Sun is losing weight all right! Not that that is a surprise, because all stars do.

But anyway, the Sun is losing weight and the Earth is gaining weight, by eating all those meteors that fall into the atmosphere of the Earth all the time.

It all adds up, I suppose.

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Re: What's it all about, Alfvén?

Post by neufer » Mon Dec 09, 2019 10:19 pm

Ann wrote:
Mon Dec 09, 2019 7:25 pm

The main point to me is that the Sun is slingshotting plasma out of its corona. Yep, the Sun is losing weight all right! Not that that is a surprise, because all stars do.

But anyway, the Sun is losing weight and the Earth is gaining weight, by eating all those meteors that fall into the atmosphere of the Earth all the time.

It all adds up, I suppose.
The Sun is mostly losing weight by slingshotting photons & neutrinos out of the solar system.

and the Earth is also losing weight by leaking hydrogen & helium.
https://en.wikipedia.org/wiki/Earth_mass wrote:
<<The current best estimate for Earth mass is M = 5.9722×1024 kg, with a standard uncertainty of 6×1020 kg. Earth's mass is variable, subject to both gain and loss due to the accretion of in-falling material, including micrometeorites and cosmic dust and the loss of hydrogen and helium gas, respectively. The combined effect is a net loss of material, estimated at 5.5×107 kg (54,000 long tons) per year. This loss amount is 10−17 of the total earth mass. The 5.5×107 kg annual net loss is essentially due to 100,000 tons lost due to atmospheric escape, and an average of 45,000 tons gained from in-falling dust and meteorites.

Mass loss is due to atmospheric escape of gases. About 95,000 tons of hydrogen per year (3 kg/s) and 1,600 tons of helium per year are lost through atmospheric escape. The main factor in mass gain is in-falling material, cosmic dust, meteors, etc. are the most significant contributors to Earth's increase in mass. The sum of material is estimated to be 37,000 to 78,000 tons annually, although this can vary significantly; to take an extreme example, the Chicxulub impactor, with a midpoint mass estimate of 2.3×1017 kg, added 900 million times that annual dustfall amount to the Earth's mass in a single event.

An additional loss due to spacecraft on escape trajectories has been estimated at 65 tons per year since the mid-20th century. Earth lost about 3473 tons in the initial 53 years of the space age, but the trend is currently decreasing. Additional changes in mass are due to the mass–energy equivalence principle, although these changes are relatively negligible. Mass loss due to the combination of nuclear fission and natural radioactive decay is estimated to amount to 16 tons per year.>>
https://www.forbes.com/sites/briankoberlein/2018/04/10/the-sun-is-losing-mass-and-getting-larger-at-the-same-time/#3933a8364ead wrote:
The Sun Is Losing Mass, And Getting Larger At The Same Time
Brian Koberlein: Apr 10, 2018.

<<The Sun's light is produced by fusion in the Sun's core. Hydrogen atoms combine to produce helium and light. The light is produced because the mass of a helium atom is slightly smaller than the mass of the four hydrogen atoms that formed it. As Einstein first pointed out, mass and energy can transform into each other, so the loss of mass means a gain of energy in the form of light. The light radiates from the Sun, warming our Earth, but that also means over time the Sun loses mass. The Sun consumes mass to produce light.

As the Sun loses mass its gravitational pull on the planets weakens slightly. The Sun can't hold the planets as strongly as it used to, so the planets drift a bit further away from the Sun. At least that's the theory. The shift of the planets is so small that it's difficult to measure. There have been some studies that seemed to see the effect with Earth, but the result isn't particularly strong. The usual method of determining planetary distance is to bounce radio signals off them, and it's difficult to do it precisely enough to determine the Sun's changing mass.

There is a much better way to measure the position of planets. Simply put a spacecraft in orbit around it. When the Cassini spacecraft was placed in orbit around Saturn, astronomers used radio signals from Cassini to measure the position of Saturn accurate to within a mile. We can do this because we know exactly what signal comes from the spacecraft, so any shift in that signal tells us how the spacecraft moves. When the Messenger spacecraft was placed in orbit, astronomers used the same technique to measure the position of Mercury. Using seven years of data they could also determine how Mercury's motion changed over time. They did it precisely enough to observe the weakening of the Sun's gravitational tug. They found that the Sun's pull is weakening by about 6.13 trillionths of a percent per year. This loss amount is ~6,130×10−17 of the total Solar mass and agrees with estimates of the Sun's mass loss due to core fusion: ~4,000×10−17 plus solar wind: ~2,500×10−17.>>
Last edited by neufer on Tue Dec 10, 2019 4:45 am, edited 3 times in total.
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Re: What's it all about, Alfvén?

Post by Chris Peterson » Mon Dec 09, 2019 10:32 pm

neufer wrote:
Mon Dec 09, 2019 10:19 pm
Ann wrote:
Mon Dec 09, 2019 7:25 pm

The main point to me is that the Sun is slingshotting plasma out of its corona. Yep, the Sun is losing weight all right! Not that that is a surprise, because all stars do.

But anyway, the Sun is losing weight and the Earth is gaining weight, by eating all those meteors that fall into the atmosphere of the Earth all the time.

It all adds up, I suppose.
The Sun is losing weight by slingshotting photons out of the solar system.

and the Earth is also losing weight by leaking hydrogen & helium.
We're losing mass to the IR we radiate into space, as well.
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Re: What's it all about, Alfvén?

Post by neufer » Mon Dec 09, 2019 10:36 pm

Chris Peterson wrote:
Mon Dec 09, 2019 10:32 pm

We're losing mass to the IR we radiate into space, as well.
Other than global warming
we lose as much mass by the IR we radiate as we gain by the visible light we absorb.
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Re: What's it all about, Alfvén?

Post by Chris Peterson » Mon Dec 09, 2019 10:41 pm

neufer wrote:
Mon Dec 09, 2019 10:36 pm
Chris Peterson wrote:
Mon Dec 09, 2019 10:32 pm

We're losing mass to the IR we radiate into space, as well.
Other than global warming
we lose as much mass by the IR we radiate as we gain by the visible light we absorb.
Of course. It's just one more factor in the calculation, though. (A small part of that energy comes from inside the Earth, so isn't balanced by solar radiation coming in.) And I think it's not entirely certain if the net change in mass is positive or negative. We have a pretty good handle on the loss of gases, but not such a good one on the total influx of dust.
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Re: APOD: Looking Sideways from the Parker... (2019 Dec 09)

Post by Boomer12k » Tue Dec 10, 2019 1:19 am

Not to mention the effects on our own magnetosphere... Solar Storms, can weaken our magnetic field...

https://www.sciencemag.org/news/2016/10 ... etic-field

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