SIOUX FALLS, S.D. (KELO) -- The coming supermoon, which will rise at 6:26 a.m. central, according to NASA, will be the largest supermoon of the year, of which there have already been three. Joel Sander, a professor in the physics department of the University of South Dakota, says that a supermoon occurs when two things -- a full moon, and the moon reaching its nearest point to Earth in its orbit -- coincide. Sander explained that this can happen because the orbit of the moon is not perfect around the Earth. While the odds of both of these instances happening at the same time seems low, Sander says that's not quite the case, and that a supermoon isn't exactly super rare. With about 12 full moons a year, it's not uncommon for 3 or 4 to match up with a time when the moon is closer to the earth in its orbit, he said. 5-year-old hit by truck and killed in Yankton In terms of how to see the supermoon, Sander noted that the moon can appear larger when it's near the horizon by way of an optical illusion. For the best view, he said you'll want to get out of town and away from lights. While a supermoon is all well and good, there is something else in the sky that is just a little bit more rare. Comet Tsuchinshan-ATLAS is currently passing by our solar system, and if you want to see it, you best get out there, because you won't be here again the next time it comes around. Comet photos submitted by Amanda SchultzComet photos submitted by Amanda Schultz Sander explained that the comet has come from the Oort Cloud, a ring of ice and dust and other particles which surrounds our solar system out beyond the reaches of Pluto. Most things which inhabit the Oort Cloud do not enter the solar system, but this comet has an orbit that brings it in. Comets, said Sander, are chunks of ice flying through space, and when they approach the sun, the ice begins to melt, being blown away off the comet by solar winds. This blowing vapor is what forms the characteristic tail of a comet. Interestingly, Sander says the comet's tail does not necessarily drift off of it in the opposite direction it is traveling, but rather comes off it on the side opposite that which is facing the sun. This is the brightest comet we've seen in about 20 years, said Sander, and the best time to see the comet is typically just after sunset when you'll want to look at the sky to the west. While the comet's tail looks rather small in the sky, Sander said that it is actually about 18 million miles long. The comet was at its nearest point to the sun about a week ago, and while it will remain visible for some time now, its light will get weaker as it moves further from the heat of the sun. As mentioned, you may want to use the chances you have now to see it. The Comet Tsuchinshan-ATLAS, said Sander, has an 80-thousand-year orbit.