Scale of all orbits in our solar system.

Scale

In the dead center lies the Sun, to scale. Every planetary orbit is a different color, though it gets hard to see the orbits of Mercury and Venus because they are so small compared to the actual size of our system. Mars orbit lies on the outside of the red circle and the asteroid belt lies within the grey area. Beyond that, on the outer edge of the next circle is Jupiter’s orbit. Saturn’s orbit takes it almost twice as far from the Sun. Twice as far as Saturn is Uranus and then, on the farthest edge of the outer, green circle lies Neptune.

This is only the scale of all of our planet’s orbits. Our solar system is multiple times larger. At least a light year or two.

If you zoom in to the center, you’ll see a white speck (the Sun). This represents how big the Sun actually is when viewed from above (and compared to the orbits). The Sun, while it is a huge 700,000 miles wide, is really quite small in the grand scheme of things. When it begins running out of fuel, it will expand (I know, counter-intuitive) into a red giant. At this point it will possibly become big enough to swallow Earth and reach the outer orbit of Mars.

Comet 67P/Churyumov-Gerasimenko – Surprise! Contact binary.

Rosetta_67PCG_14July_2014

So Rosetta is landing on this comet soon. As it got closer there was talk that the comet may be two-fee, two comets orbiting a barycenter. That is probably what it was at one point in time, however now it is a contact binary. These two nuclei began fusing somewhat recently into what now looks like a rotating rubber ducky without a beak. Go, go, go!

One year from today we arrive at Pluto (Why is that so badass?)

This is pretty cool because we really only have suggestive ideas about what it looks like. I always felt that they should have launched two satellites but not as a failsafe.

You see, Pluto changes over the course of a year. Not an Earth year, a Plutonian year. However, a year on Pluto is so long that to get any meaningful new pictures or data from it, you’d have to send the second one in 50-100 years so.. I guess maybe sending one was alright.

Pluto has a crazy orbit. People mostly know that it has a tilted orbit that tilts quite a bit, and also that it sometimes comes closer to the Sun than Neptune.  That’s only a piece of what makes Pluto odd and, consequently, interesting.

Pluto_animiert_200px

FACTS THAT MAKE PLUTO PRETTY DAMN COOL

- Let’s not talk distance in miles. Let’s use AU (Astronomical Units). One AU is exactly this average distance from the Earth to the Sun. Hence, Neptune’s orbit takes in anywhere between 29.8 and 30.4 AU away from the Sun. Considering it over billion miles from the Sun, it is almost a perfect circle. And yes, Pluto does dip within Neptune’s orbit but it is nothing close to a circle. Pluto’s orbit takes it between 29.7 and 39.3 AU.

- This means that it’s closest approach to the Sun is nearly a billion miles closer than it’s furthest approach.  To convey how far a billion miles is I will put it in two other ways – 1) Saturn orbits the Sun at about a billion miles. 2) Jupiter is closer to the Sun than Saturn. Much closer than most people think, at about a half of a billion miles. A billion miles (just over 10 AU) is a long, long way.

- Pluto has an atmosphere, we believe. Why does the whole billion miles thing matter in terms of atmosphere? The same reason we need to send another satellite here in a little while. At Pluto’s farthest point, it is so far away and so cold that the gas making up it’s atmosphere is frozen solid to the dwarf planet’s surface. Hence, changing it’s appearance. The photos directly below show what changes this could potentially bring. As far away as we are, we have detected odd changes to Pluto’s surface which lend credibility to this theory.

images-3 images-4

- On it’s close approach the atmosphere melts and surrounds the (dwarf) planet.

- It is so small. A sixth of the mass of the Moon.

- Somehow, despite it’s size, it may have rings.

- Also, again, despite the size, it has at least 5 moons. Maybe. It probably has more. It’s so far that we discovered the first moon Charon in 1978. Nix and Hydra were discovered in 2005. Kerberos was discovered by the Hubble in 2011. The fifth moon, Styx, was discovered in 2012. However, like the gas giants, that number of moons will most likely increase once we get a satellite within range.

- Pluto’s designation as a dwarf planet may still evolve. Charon (Pluto’s largest moon) may also not technically be a moon. Together, Pluto and Charon may be a binary (dwarf) planetary system. Why is this? See, most systems have a planet with orbits the sun, and the moons directly orbit their host planet. Pluto and Charon defy this model. Yes, Charon orbits Pluto, however Pluto also orbits around a central point. Nothing is within this point (a barycenter, not to be confused with lagrange points). This is similar to binary star systems which are very common. Our sun is odd being that it doesn’t have a partner star. If it did, it would also mostly likely orbit a small point like Pluto does due to interactions with the mass of it’s sister star, making it a binary system. Hence, Pluto may soon be designated as a binary system with Charon.

300px-Pluto-Charon_double_planet

 

-  There are actually many, many other dwarf planets. Pluto is not even the largest of them, which is what prompted the community to find another designation for it being that, otherwise, we’d have a few dozen planets. Eris is another dwarf planet, the largest of all that we have discovered to this point. However, it is much further away from the Sun.

- Did you know there was another planet that was downgraded from planet to dwarf planet? Did you know it can be seen with the naked eye (sometimes)? It’s name is Ceres and is the only dwarf planet  in the asteroid belt beyond Mars. The Dawn satellite will reach Ceres in 2015, making this coming year the next foreseeable time where we will get high quality photos of a world within our reach we have yet to really see. Ceres is pictured just below, along with an artists interpretation and comparison between Ceres, Pluto and Eris.

Ceres_optimized dwarf_planets_compared_800

- Pluto is smaller than a number of moons:
These are Ganymede, Titan, Callisto, Io, Europa, Triton, and the Earth’s moon. Pluto has 66% of the diameter of the Earth’s moon and 18% of its mass.

- Pluto is named after the Greek god of the underworld:
This is a later name for the more well known Hades and was proposed by Venetia Burney an eleven year old schoolgirl from Oxford, England. The moons are also named within this theme.

- Pluto’s location was predicted by Percival Lowell in 1915:
The prediction came from deviations he initially observed in 1905 in the orbits of Uranus and Neptune.

I am sure this list will grow within the coming year.