The speed of orbit around a galaxy depends on the distance from the galaxy's center. For objects in circular orbits around a point mass, such as a galaxy, the orbital speed is given by:

```

v = √(GM/r)

```

where:

* v is the orbital speed in meters per second (m/s)

* G is the gravitational constant (6.674 × 10^-11 N m²/kg²)

* M is the mass of the galaxy in kilograms (kg)

* r is the distance from the galaxy's center in meters (m)

For example, the Sun orbits the center of the Milky Way galaxy at a distance of about 8 kiloparsecs (2.5 × 10^20 m). The mass of the Milky Way is estimated to be about 1.5 trillion solar masses (3 × 10^42 kg). Therefore, the orbital speed of the Sun around the galaxy is:

```

v = √((6.674 × 10^-11 N m²/kg²) × (3 × 10^42 kg) / (2.5 × 10^20 m)) ≈ 220 km/s

```

This means that the Sun travels at about 220 kilometers per second (137 miles per second) in its orbit around the galaxy.