"Its orbit passes between the sun and any given point on Mars about once each Earth year. Each time it does so, it causes from one to seven solar eclipses withi

"Its orbit passes between the sun and any given point on Mars about once each Earth year. Each time it does so, it causes from one to seven solar eclipses within the space of three days." Does anyone have an explanation of how this works? Seven solar eclipses seems like a lot and I can't seem to visualise what is happening, presumably it's Mars spinning and Phobos staying still that causes this, but I can't understand why the difference is so huge.