Why Phobos is dieing

Phobos is a small, irregular shaped object with a mean radius of eleven km and is seven times as massive as the outer moon, Deimos. It is one of the least reflective body in solar system.

Solar transits

An observer on Martian surface who would observe Phobos, would see regular transits of Phobos across the sun.

Phobos is not large enough to cover the sun's disk and so cannot cause a total eclipse.

It is destroyed by tidal deaccelaration and it is also torn apart by tidal forces, which leads to a fraction of debris to form a planetary ring around mars which may last for one million to one hundred million years.  It's origin is still controversial.

Diameter:	22.2 km
Mass:	1.07 × 10^16 kg (0.00001% Moon)
Orbits:	Mars
Orbit Distance:	9,376 km
Orbit Period:	7.7 hours
Surface Temperature:	-40 °C
Discovery Date:	August 17, 1877
Discovered By:	Asaph Hall

Facts about Phobos :

1. The innermost and largest of the two natural satellites of mars.

2. It is so close that it orbits mars much faster than mars rotates and complete an orbit in just 7 hours and 39 minutes.

3. It may destroyed in approximately in 30-50 million years after due to tidal deaccelaration.

4. Phobos’s shadow has been photographed on the surface of Mars by several spacecraft.

5. Phobos is roughly potato-shaped and has a large crater called Stickney