We've talked a few times on this list about the sheer size of the Sun. You could fit the Earth inside it a million times and still have room to spare. It takes an individual photon of light 170,000 years to get from its core to its outer edge. So what if we told you that, on a galactic scale, it's actually pretty feeble?
The largest star scientists are currently aware of is UY Scuti, which is 9,500 light years away and forms part of the constellation of Scutum. It is almost exactly 1,708 times larger than our own Sun. To give you an idea of what that means in terms of our Solar System, if you swapped out our Sun and put UY Scuti in its place, its outer edge would touch on the orbit of Saturn, and Mercury, Venus, Earth, Mars and Jupiter would be completely swallowed up inside it.