Sorry best I could do

The instructor had a 14" Go-To scope, so after we viewed the assigned objects I asked if we could find the giant ice planets. Sure enough, when he dialed in Uranus, there it was! As a bonus, Neptune was also up! Since we had observed Venus, Mars, Jupiter and Saturn early in the semester, and I had caught Mercury on my own earlier, this meant I had a complete sweep of our planets.

I know it doesn't sound like a big deal to non-stargazers, but to have seen all eight planets in our Solar System feels like a bucket list item to me.

It should have been nine planets, but f*ck you, Neil deGrasse Tyson, for killing Pluto.

Still impressive though at 4 billion miles.

How sure are you that we don't have more than eight planets in the solar system, even with Pluto being downgraded? Say, if a planet moves at roughly the same speed as Earth and was on the opposite side of the Sun (it would have to move at almost exactly the same speed, within fractions), we would never know it is there given our current capabilities. Even Voyager I and II and other probes communicating with Earth would not image it due to the orientation they would forever have relative to that planet.

According to an article entitled, "Could There Be Another Planet on the Other Side of the Sun?" (Futurism.com):

In a solar system with only two bodies of equal mass, the idea of an "anti-Earth" is a staple of science fiction lore. Once you add Jupiter into the mix, however, everything changes.

As the Earth orbits the Sun, it’s subtly influenced by those other planets, speeding up or slowing down in its orbit.

So, while we’re being pulled a little forwards in our orbit by Jupiter, that other planet would be on the opposite side of the Sun. And so, we’d speed up a little and catch sight of it around the Sun. Over the years, these various motions would escalate, and that other planet would be seen more and more in the sky as we catch up to it in orbit.

Eventually, our orbits would intersect, and there’d be an encounter. If we were lucky, the planets would miss each other, and be kicked into new, safer, more stable orbits around the Sun. And if we were unlucky, they’d collide with each other, forming a new super-sized Earth, killing everything on both planets, obviously.

If the other planet on the other side of the Sun had almost identical mass as Earth (within a fraction), almost identical gravity and Revolution speed, would it take millions of years for us to get a peak, tens of millions of years beyond the time that we have had such capability?

Gravity affects everything in the universe. In our solar system, the two biggest influences are the Sun and Jupiter. The latter was the first planet to form, and at one time its orbit was inside that of Mars before Saturn yanked it back to its present position. ("Yanked" being a relative term -- it took millions of years for Jupiter to spiral in and out of its orbit.)

While you're right that it would take a long time to see a counter-Earth, it doesn't mean we can't know it's there right now.

Here are a bunch of people who are a lot smarter than me discussing the same topic.

Essentially, while we may not be able to visually identify the counter-Earth for a long, long time, we have the science to identify it now, based on its gravitational effects on other planets that pass by it.

NASA has two satellites in stable positions along the Earth's orbit which are located on the other side of the Sun. It is called the STEREO mission, and is designed to let us see the far side of the Sun in real time, so the data can be compared to that acquired by Earth-side probes, like SOHO.



NASA also worked together with the European Space Agency on the Ulysses mission, which circled the Sun in a polar orbit.

Between observations of planetary perturbations and direct observations by solar probes, if there were anything on the other side of the Sun, I'm pretty sure we would have detected it by now.

Neither is on the other side of the Sun from Earth. That would not allow signals for one thing and second, would not support orbiting of the craft that is out of Earth's gravitational influence. I have read up pretty extensively on STEREO and initially thought that one was on the opposite side of the Sun, but more detailed reading led to me dropping that.

If there was an Earth twin on the other side of the Sun, the gravitational influence of other planets on Earth and that twin should create a null result, such that the properties of Earth and the twin alone determine where they are.

I also read up on the planet accretion theory (how planets formed). It goes that a disc of mass separated from the Sun then got pushed outward forming planets as it moved out. If you look at all the terrestrial planets, they are ordered perfectly by size, except for Earth and Mars. Mars could have been bigger than Earth at one time and got split sometime within it's first 100 million years, but if that did not happen, that throws a big wrench in the accepted theory of how planets reordered, as does Neptune and Uranus being where they are (unless another Star or a dwarf Star influenced the formation of our solar system early on). I am sure that you understand that there still is debate about how the solar system formed, very capable people are lining up on both sides of that debate, that is why we do exploration to provide more answers.

Seems like once you get far enough away from the Earth, unless you're travelling in the orbital plane ... at some point you'd 'clear' the sun, and it'd stop acting as an obstruction to the craft being able to see what's on the other side of the sun. What am I missing?

Something along these lines:

V
*.*
*...*
*.....*
*.......*
*.........*
*...........*
E***S***ME

V=Voyager
E=Earth
S=Sun
ME = Mirror Earth

Of course, I can just be a solar system formation truther. But anything that has 2+ theories on it's formation causes legitimate doubt. Of those 2+ theories, very smart people can give convincing arguments to support either and use information that has been collected over time to buttress their argument.

impossible to put something in a position to be able to see a 'mirror earth', yeah?

I would think it would definitely be possible, if someone sought that particular goal.

But your arguments are as valid as any that I try to make. One thing that interests me is the socalled Dark Matter, it's existence has been theorized and widely accepted by astrophysicists, but every single attempt to prove it's existence has failed.

What is dark matter is not matter but is something like a force? Such a theory would explain a massive number of space phenomena.

with a craft like Voyager ... didn't properly understand the parameters i.e. neither Voyager was heading in the direction it would need to be to see a ME (mirror earth for short), not that it was impossible as a concept in general.

Don't know too much about Dark Matter other than it's existence theorized due to mass calculations not 'adding up', such that there 'must be' matter, with considerable mass, in the universe, that we lack the ability to detect.

Not a physicist by any stretch, but I have taken courses ... and I have to say, from my basic understanding, I'm not sure how a 'force' would have 'mass'?

Or are you saying this 'force' is causing us to miscalculate the mass we'd be expecting to see (and hence caused the presumption of existence of dark matter originally)?

in the possible existence of something called dark matter, but also it caused miscalculation on how celestial bodies originally developed their orbits (disputes the notion of primordial inertia being the source of celestial body orbits) and maintain those orbits over billions of years, even with collisions and the incessant gravitational attraction of the massive Sun on planets (in the case of our solar system) or Sag A on star systems (in the case of the Galaxy). It is crazy stuff, no need to go into it any further, it's sort of out there.

The two STEREO spacecraft, labeled "STEREO A" and "STEREO B," are each in their own orbit around the sun. They are quite free of Earth's gravity. After their launch, NASA used the Moon for a gravitational slingshot to move them into orbits where one is slightly closer to the sun than the Earth, the other slightly more distant. As a result, the closer-to-the-sun one orbits faster than the Earth and has moved "ahead" of us (STEREO A), and the further-from-the-sun one orbits more slowly than Earth and has moved "behind" us (STEREO B). They moved ahead and behind, and then further ahead and further behind, until first the A , then the B, passed around the far side of the sun several years ago. They are now continuing in those orbits and are halfway back to Earth. See
https://gong2.nso.edu/products/scaleView/view.php?configFile=configs/pfssModels.cfg&productIndex=6
for a map, generated hourly, showing where they are right now in a view looking down at the Sun's and Earth's north poles.

While the spacecraft were behind and almost behind the sun, indeed, we would not have been able to receive their signals, and so they were put into a standby mode for a few weeks.

If there were an Earth-sized body on the opposite side of the sun, the orbits of these two spacecraft would have been altered by it and those who aim the antennas to pick up their signals would have not found the space craft to be where they were expected to be. There is no hidden planet opposite the Sun from us.

See https://www.nasa.gov/mission_pages/stereo/main/index.html for lots of info on the STEREO mission and findings.

Signals from anything on the other side of the Sun from us would be impossible unless there was a relay (or several of them) craft positioned in very deep space of the solar system and those craft would have to stay coordinated with each other, the STEREO craft and Earth. In the little that I have read, I have not read about such relay craft in operation.

I just may be a solar system truther and that has led to other things with me. I started out with a hard time imagining how something that is 25,000 lightyears from Sag A could form from gravitational collapse (even there scientists of various thought have come up with at least 2 theories on how that happened, neither proven). For a long time Astrophysicists rather conclusively believed that it was impossible for a star to be beyond a certain mass, yet at least two have been found in deep space that are something like 500 times more massive than stars which scientists said could not exist for more than a few million years, the Stars could no longer exist, but the fact is they formed, how? A group of scientist that were looking over space telescope data have discovered that Sag A is surrounded by millions of stellar black holes on the side of Sag A where we can see them, how can that happen and what is the relationship and interaction between Sag A and the black holes that surround it?

Like I said, I just may be a space truther (but definitely agree that the Earth is a sphere), I question existing space theories that many accept as truth and pull of data to "prove" (no knock on you, it is just I have issues arriving at the same conclusion).

One of the comforting things about religion is people who believe can just accept the existing "proof" that something is true (no knock on them, they could be right, though as more is discovered they being right becomes less and less probable). I have always been a questioner, so acceptance of something that I see holes in is difficult for me.

I just finished at the local community college. Unlike the math-heavy class I took many, many years ago at Mizzou, it was only a descriptive course, and didn't discuss any of the questions you've presented.

It also appears our (very expensive) textbook is behind the times. We learned the Nice (named after the city) model was the generally accepted description of solar system formation; now there at least three other theories. That's the neat thing about science -- as we gain more information existing theories are modified or discarded completely.

Since this discussion has gone well beyond my knowledge and abilities, I'll close now. I truly appreciate the topic, and your thought-provoking and well-informed posts. Thank you, Blue_true.

There are a number of Kuiper Belt objects which have been pulled out of the normal orbital plane of the Solar system; all seem to be tugged gravitationally by an object perhaps 10x the size of Earth. If there, it will be extremely faint and hard to find, but astronomers are hard at work to find it.

Learning Pluto was a damn planet.
Its a damn planet.
Dammit.

Our Sun probably latched onto it many, many years ago.

Its sun probably was a G2V like ours then died and lost it.

Planet 9 would be a nearly-lost one that just managed to cling to an orbit.

There are, however, many "rogue" planets flying around out there between solar systems; victims of similar formative processes in their own home systems. Probably our own system lost a couple of planets.

I looked it up, the Mass of Uranus is 14x that of Earth. Wouldn't Planet 9 have to be much larger than 14x earth mass to defeat Uranus and move Kiper Belt bodies? Could Planet 9 be a brown dwarf star that is capable of fighting the Sun (but always losing)?

The postulated 9th planet would only have to explain displacements of a few dozen (known) bodies, which would have been pulled from the outer edge of the Kuiper Belt, about 50AU from the Sun (nearly twice the diameter of Neptune's orbit.

- with a nice mention to his sister Caroline, discoverer of comets.

it's a 6" dobsonian. Was a little light blue disk just like what I was expecting. The only planet I haven't seen is Neptune which is on my list to try for later this year, along with maybe Pluto.

#astronomygoals

Its small, very blue and like other planets, doesn't "twinkle" like stars do.

The challenge is Pluto. You basically have to do it like Tombaugh, look in the general area and watch for movement over successive nights.

By the way: Herschel wanted to name his new discovery after George III. Perhaps he thought that the king needed a consolation prize.

From NASA/JPL: Uranus, as seen from the Cassini spacecraft in 2014

...Uranus is a pale blue in this natural color image because its visible atmosphere contains methane gas and few aerosols or clouds. Methane on Uranus -- and its sapphire-colored sibling, Neptune -- absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space, resulting in the predominantly bluish color seen here. Cassini imaging scientists combined red, green and blue spectral filter images to create a final image that represents what human eyes might see from the vantage point of the spacecraft.
...

Uranus was approximately 28.6 astronomical units from Cassini and Saturn when this view was obtained. An astronomical unit is the average distance from Earth to the sun, equal to 93,000,000 miles (150,000,000 kilometers).

This view was acquired by the Cassini narrow-angle camera at a distance of approximately 614,300 miles (988,600 kilometers) from Saturn on April 11, 2014. Image scale at Uranus is approximately 16,000 miles (25,700 kilometers) per pixel. Image scale at Saturn's rings is approximately 4 miles (6 kilometers) per pixel. In the image, the disk of Uranus is just barely resolved. ...

https://photojournal.jpl.nasa.gov/catalog/PIA17178:

someone's idea of a joke. Then I saw a circle labeled Saturn then Jupiter then Mars. I found out it was the scale model of the distance from the sun to the planets.