Jupiter.

The Earth would fit inside Jupiter 1324 times! It may not appear to be that much bigger than Earth, but, the way someone described it to me was: Because of the mass of Jupiter, it would be like a balloon, the planet would stretch , just like a balloon. Just like a balloon stretching to hold more water or anything else you put in it, Jupiter would, THEORETICALLY, stretch whenever you put something inside of it. It would stretch out enough to where All the other planets, including Pluto, would fit inside of it!
The famous, Great Red Spot is about Three times bigger than Earth.
It is a large storm that's been going on for over 300 years. It is currently, slowly shrinking. It spins counterclockwise at about 225 MPH (360 KPH). It is comparable to a hurricane.
Jupiter would fit inside the Sun 9 times.
It has a faint ring system. Scientists did not know about the rings until the Voyager Spacecraft got there. Voyager showed the rings for the first time. The rings are too faint to be seen with a Telescope. In fact, I have a really powerful Telescope and I can't see the ring with it. University of Central Florida in Cocoa, FL has the second largest Telescope in the state of FL and they can't see it with that scope.
It has, as of now, 69 confirmed Moons. Probably, more to be found.
Looking through my Telescope, I can see the color bands on the planet and Six of it largest Moons.
Since, Galileo invented his own Telescope and looked at Jupiter, and discovered 4 of these same Moons (Io, Europa, Ganymede & Callisto), they are called: Galileo Moons. Those are Jupiter's largest moons. The rest are too small to see from Earth.
(Unfortunately, someone else invented the Telescope, just a short period of time before Galileo invented his telescope. So, he can't claim credit for inventing it.)
There are some very violent storms on Jupiter. Mostly inside the planet. Lightning on this planet is much more powerful than what we experience here on Earth. Scientists believe that it rains Diamonds inside of Jupiter. Because of the heat and pressure inside of the giant ball of Gas. But, they can't prove it.
The composition of the planet is mostly: Hydrogen, Helium and Ammonia. It's believed to have a rocky and metallic core.
Since the planet spins so fast, it completes one rotation in 9.8 Earth hours.
The rapid rotation causes Jupiter to bulge at the Equator. The diameter at the Equator is: 88,846 Miles (142,948 K).
The diameter at the poles is: 83,082 Miles (133,708 K). The Scientific name for this shape is: An Oblate Spheroid.
Jupiter is a Brown Dwarf. A failed star. Since it is made up of the same elements as most stars. However, it would have to be 75 times more massive to cause nuclear fusion of Hydrogen and turn into a star.
The color bands around Jupiter are created by strong 400 MPH (640 K) winds flowing East to West in the planets upper atmosphere.
Jupiter has a huge magnetic field, larger than any other planets. It is also the strongest magnetic field in our Solar System. It's almost 20,000 times strong than the one here on Earth! It is more than 1,000 times the lethal dose of radiation for a human. This magnetic field damages every spacecraft that goes near it, even if it is heavily shielded. The magnetic field extends out between 600,000 - 2 Million Miles (1 Million - 3 Million  K) towards the Sun and forms a tail which extends over 600 Million Miles (1 Billion K) behind the planet.
At it's furthest point from the Sun Jupiter is 507.04 Million Miles away.
When it's closest to the Sun it's 460.24 Million Miles away.
It orbits the Sun at a speed of 29,205 MPH. Completing one rotation around the Sun in 11.86 Earth years.
The distance from Jupiter to Saturn depends on where they are in orbit. When they are on the same side of the Sun and at their closest point, they are approximately 5 Astronomical Units (AU) away from each other.
When they are on opposite sides of the Sun, they are about 15 AU away from each other.
(One AU is the average distance between the Sun and Earth. 93 Million Miles or 149,668,992 K).
Depending on where the Earth and Jupiter are in their orbits, Jupiter is between 4.2 and 6.2 AU away from Earth.
We are lucky to have a planet the size of Jupiter in our Solar System, because, being so big, it has a lot of gravity. It attracts a lot of Metiors and other things to it. So, rather than hitting Earth or the other planets, a lot of them hit Jupiter instead.
Imagine what might have happened if Shoemaker-Levy would of hit Earth.
The SL comet had been captured by Jupiter's gravity about 20 or 30 years before it broke into several large pieces and hit Jupiter in July of 1994. The fragments of the comet got too close to the planet on July 16, 1994. The first impact created a fireball larger than Earth! A total of 21 impacts were observed over the next six days. The largest one created a dark spot more than 7,456 Miles (12,000 K) across. The explosion it created was 6 Million Megatons of TNT. That's 600 times the worlds entire known nuclear arsenal at that time, according to: www.americaspace.com.
A comet or meteor that size hitting Earth would quickly put an end to all life on Earth! In fact, most Scientists believe that it was a large meteor that crashed into Earth 65,000,000 years ago that killed off the Dinosaurs.

Aliens in the Milky way Galaxy.

The Milky Way Galaxy is approximately 100,000 Light Years across. We are are near the far end of one side. If aliens have tried to contact us all the way from the other side and they were 90,000 LY away, their message wouldn't reach us for 90,000 years after the day they sent it. That is only if they used a Radio Telescope like Scientists use here on Earth. That's because radio waves travel at about the speed of light thorough space.
Assuming they are much more intelligent and much more advanced than Humans and they've invented a UFO that can travel ten times the speed of light and they are also able to survive the G Force, it would still take 9,000 years to travel to us.
They could also have a time warp or, better yet, use Einstein's theory of "Bending Time and Space", which is only theoretically possible, where you could bend two points in space and bring them together. Then they would be able to pull our Solar System to wherever they are and just fly across within only a few Seconds! That would be so cool, but highly unlikely.
However, there's also a small chance that they will be less intelligent than us and they can't even figure out how to get off the ground of their own planet. I doubt that though. But, if that were true, or even if they had a big spaceship traveling towards us from 90,000 LY (27,607 Parsec) away, we still wouldn't be able to see them with the world's most powerful Telescope, which is called: "The James Webb Telescope". It will be much more powerful than the Hubble. They haven't even sent it up yet. NASA will launch it up within a few years. I don't know how, unless they get our space program going here again by that time. Otherwise, they will have to contract it out and have either one of the civilian agencies like Space X do it or Russia may have to send it up for the US.
If the aliens are outside of our Galaxy, they will be able to get in the Milky Way to visit us, but it will be extremely difficult for us or them to get out of our Galaxy. Because, the Milky Way is so big, and so strong that, Because of all of its gravity and several other forces of Physics, which I don't understand, you would have to travel about 1.2 Million miles per hour to get out of the Milky Way! That is the Escape Velocity of the Milky Way Galaxy.
If you did get out though, you may have a much easier time getting back in, but, since the spiral arms of the galaxy are rotating pretty fast, the whole galaxy will be flying away from you through space and our entire Solar System is moving through the inside of the galaxy,  if you did get back inside, you would be a long ways away from where you started from and you'd be far away from the Earth. Good luck finding it again!
Personally, I believe aliens have already been here, who do you think built the Pyramids 5,000years ago? As well as Crop Circles and other things.
(BTW, one Parsec is approximately 3.2 Light Years.)