What is that nebula near the constellation Aries?
There’s not much there. If you have exceptional eyesight and a dark sky location, you might be seeing M33, the Pinwheel galaxy, which is just north of Aries in Triangulum. Moving north, other possibilites are M31, the Andromeda Galaxy; M34, an open cluster in Perseus; or the Alpha Persei Moving Cluster, centered around Mirfak. But perhaps the best possibility is that you’re seeing Comet Holmes, which is in Perseus right now and quite bright.