I witnessed what appeared to be a moving aircraft and noticed no beacon lights flashing then I thought it may have been a star

I witnessed what I thought was an aircraft without any flashing beacon lights. Then I thought it may have been a star moving across the sky slowly I watched it move across the sky for roughly 4 to 8 seconds and the light just disappeared as if it were turned off the sky conditions are crystal clear. It appeared to be the size of white or bright star in the sky would be and it was very high in the atmosphere. It made no sense just moved across the sky and suddenly appeared and disappeared