Why are there no nebulas visible in the night sky...I mean nebulas large enough to be seen with the naked eye? The answer is that there's several. They're just faint because they're so close.
A lot of the bright nebulas you see in photos are color enhanced, are shot with time lapse photography, and are composites. Given those advantages they look great. If they were closer and untreated, most would look as dim as our local samples.
Here's a few of the nebulas visible in the Southern sky. The biggest ones are Barnard's Loop and the Gum Nebula. On a clear night all are visible with the naked eye. Of course the Magellanic Clouds (actually small captive galaxies) are visible with the naked eye and so is The Milky Way.
Here's a clearer telescopic shot of the Gum Nebula. The name comes from Gumm, the astronomer who discovered it in the 1950s.
In the middle of the picture you see "Vela SNR". That's short for the Vela Supernova Remnant.
BTW, have you been paying attention to the close shots of Jupiter we're getting from the Juno probe? They're awesome! The picture above was made without color code manipulation.
Here's (above) what Juno saw when it flew over Jupiter's North Pole in mid-May. Watch it on the biggest screen that you can.
