Simplify the following text for a Grade 8 native English-speaking person.
Original: Based on observations taken by Voyager and since then with the Hubble Space Telescope , Neptune appears to spend somewhat more than half its time with a Great Dark Spot .
Simplified: Based on pictures taken by Voyager and since then with the Hubble Space Telescope , Neptune appears to spend a little bit more than half its time with a Great Dark Spot .