**Interstellar Dust Hypothesis**

The Interstellar Dust Hypothesis proposes that planets are formed from the accumulation and accretion of interstellar dust and gas. This hypothesis suggests that the embryo, or protoplanetary disk, grows in size through the process of accretion, eventually forming planets.

**Explanation**

1. **Formation of Protoplanetary Disk**: According to the hypothesis, the initial stage of planet formation begins with the contraction and collapse of a cloud of interstellar gas and dust. As the cloud collapses under its own gravity, it forms a rotating disk called a protoplanetary disk.

2. **Accretion**: Within this protoplanetary disk, solid particles, including dust and ice grains, begin to collide and stick together due to electrostatic forces. These collisions and accretion processes cause the particles to grow in size.

3. **Formation of Planetesimals**: As the solid particles continue to collide and accrete, they eventually form larger bodies known as planetesimals. These planetesimals can range in size from a few kilometers to several hundred kilometers in diameter.

4. **Formation of Embryos**: The planetesimals further collide and merge to form even larger bodies known as planetary embryos. These embryos are intermediate in size between planetesimals and fully formed planets.

5. **Growth into Planets**: Over time, the planetary embryos continue to grow in size through further collisions and accretion. Eventually, they reach a critical mass where their gravitational pull becomes significant enough to attract and capture gas from the surrounding protoplanetary disk.

6. **Formation of Planets**: As the planetary embryos accrete gas, they undergo a process known as gas accretion or gas capture. This process allows the embryos to gather more mass and eventually become fully formed planets.

**Conclusion**

In summary, according to the Interstellar Dust Hypothesis, the embryo formed through the aggregation and accretion of interstellar dust and gas grows in size to form planets. The process involves the formation of a protoplanetary disk, followed by the growth of solid particles into planetesimals and planetary embryos. These embryos then continue to accrete material, including gas, and eventually become planets.