So here we are, the end of the major planets of our solar system. I know some of you are still thinking: "Yah whatever, Pluto will always be a planet to me. To you I say go read some scientific papers by the people who work at NASA. Some of them are surprisingly interesting and to be honest, the explanations they give make complete and total sense. For those of you interested in reading a simpler explanation from an actual authority, here's NASA's explanation:
PLUTO ISN'T A REAL PLANET GET OVER IT.
Neptune
One of my favorite things about Neptune is the way it was discovered. Scientists had recently discovered Uranus and after mapping its orbit, realized that something else was having an affect on Uranus' orbit. It was hypothesized that there must be another large planet that had yet to be discovered and sure enough, less than 20 years after the irregular orbit had been observed, Neptune was discovered in 1846. Normally, I don't really care all that much about how the planets in our solar system were discovered. Not that the stories aren't cool, but at the initial point of discovery we always know very little about said planet or body and it isn't until much later that we start learning really cool things about them. I just enjoy that Neptune was the first planet discovered through mathematical means rather than through empirical observations by humans on the ground.
The picture above shows as size comparison between the Earth and Neptune, Earth has a diameter of about 7,918 miles while Neptune has a diameter of 30,599 miles (just over 3.8 times larger than the Earth). Now, most people when they think of Neptune, they think a cold gas planet at the edge of our solar system. While this view is partially correct, as Neptune does in fact contain a massive amount of hydrogen and helium, we now know that what makes Uranus and Neptune different from Jupiter and Saturn is the presence of massive amounts of water ice, ammonia ice, and methane ice.
As you can see from the image above, Neptune has several main layers, very similar in composition to Uranus. A deep outer layer of hydrogen, helium, and methane (which gives Neptune its blue color) and than an inner layer of "ice." Now, ice is a term used here in very loose terms because really, while there is in fact some legit water ice, the sheer amount of mass and resulting gravitational forces cause these compounds to behave so strangely that they are often referred to as an icy-ammonia-methane-ocean even though the layer is actually a very dense and very hot liquid (type thing, they really don't know what the heck it really is). Now, we know that Neptune and Uranus are composed of pretty much the same things, but one thing we do know is that Neptune is for some reason a lot more active on the surface than Uranus is.
Storms on Neptune experience the fastest winds and some of the coldest temperatures in the solar system, reaching speeds of 1,300 miles per hour and temperatures as low as -360 degrees Fahrenheit; seriously cold. We know why the planet should be cold as it is over 2.78 billion miles from the Sun, but why should a planet that receives very little energy from the sun have storms with winds that are consistently over 1300 miles per hour? Scientists believe that a combination of internal heat and sheer lack of friction are the causes. With nothing majorly solid getting in the way, the winds have been getting faster and faster over millennia and who knows if they will ever slow down. Neptune even had it's own super storm: "The Great Dark Spot" much like Jupiter's great red spot, was a storm that had been active since scientists first discovered Neptune and who knows how long before then. Until in 1994, scientists could no longer see the storm on the surface; it had either finally stopped or has become obscured. In addition, like all of the large planets, Neptune has a small ring system probably leftovers from the formation of the planet billions of years ago.
Picture of Neptune's rungs as imaged by Voyager. Neptune itself has been blacked out.
Neptune also has 13 known moons, although there are probably a lot more we have yet to discover, with the largest being Triton (Triton contains 99% of the mass of all of Neptune's moons).
Triton is the seventh largest moon in the solar system with a diameter of 1,700 miles and is the only large moon with a retrograde orbit (it orbits the opposite way that Neptune rotates) and because of this, scientists believe that Triton was formed elsewhere and later gravitationally captured by Neptune.
Our moon, Triton, and the Earth
This is further proved by the fact that this retrograde orbit is causing Triton to slow down and will eventually cause Triton to either fall into Neptune or be ripped apart by the sheer force of gravity. Triton is also famous for having some of the coldest temperatures in the solar system, so cold in fact, that 55% of the surface is covered in nitrogen ice (nearly -400 degrees Fahrenheit). The other 12 moons are all shaped funny and have no seriously interesting facts about them so I'm not going to bother mentioning them.
And now we have arrived at the end of the major planets. The next blog will cover pretty much all of the rest of the Solar system: the Kuiper belt, dwarf planets, and the edge of the solar system; stay tuned.
When I was younger, I thought it strange Uranus could never be discovered mathematically from Saturn’s orbit as Neptune was from Uranus’. I imagined that by 1700 people would have calculated the orbit of Saturn well enough that any irregularities would have been noted and that these would have been real.I was unsure that irregularities in the orbit of Saturn would be attributed to a seventh planet, but assumed Uranus must have some influence thereon.
ReplyDeleteWith hindsight, however, it is easy to see why Uranus was not discovered from observing the orbit of Saturn: Uranus cannot perturb Saturn’s orbit significantly as it is one-seventh the mass of Saturn and one twenty-second the mass of Jupiter, besides being much further from Saturn than out largest planet. In contrast, Neptune is larger than Uranus and Uranus is further from the major gravitation field of Jupiter than is Saturn.