<Table> Milky Way Galaxy <Tr> <Td_colspan="2"> The Milky Way's Galactic Center in the night sky above the Paranal Observatory (the laser creates a guide - star for the telescope). </Td> </Tr> <Tr> <Th_colspan="2"> Observation data </Th> </Tr> <Tr> <Th> Type </Th> <Td> Sb, Sbc, or SB (rs) bc (barred spiral galaxy) </Td> </Tr> <Tr> <Th> Diameter </Th> <Td> 100--180 kly (31--55 kpc) </Td> </Tr> <Tr> <Th> Thickness of thin stellar disk </Th> <Td> ≈ 2 kly (0.6 kpc) </Td> </Tr> <Tr> <Th> Number of stars </Th> <Td> 100--400 billion (2.5 × 10 ± 1.5 × 10) </Td> </Tr> <Tr> <Th> Oldest known star </Th> <Td> ≥ 13.7 Gyr </Td> </Tr> <Tr> <Th> Mass </Th> <Td> 0.8--1.5 × 10 M </Td> </Tr> <Tr> <Th> Angular momentum </Th> <Td> ≈ 7067100000000000000 ♠ 1 × 10 J s </Td> </Tr> <Tr> <Th> Sun's distance to Galactic Center </Th> <Td> 26.4 ± 1.0 kly (8.09 ± 0.31 kpc) </Td> </Tr> <Tr> <Th> Sun's Galactic rotation period </Th> <Td> 240 Myr </Td> </Tr> <Tr> <Th> Spiral pattern rotation period </Th> <Td> 220--360 Myr </Td> </Tr> <Tr> <Th> Bar pattern rotation period </Th> <Td> 100--120 Myr </Td> </Tr> <Tr> <Th> Speed relative to CMB rest frame </Th> <Td> 631 ± 20 km / s </Td> </Tr> <Tr> <Th> Escape velocity at Sun's position </Th> <Td> 550 km / s </Td> </Tr> <Tr> <Th> Dark matter density at Sun's position </Th> <Td> 0.0088 M pc or 0.35 GeV cm </Td> </Tr> <Tr> <Td_colspan="2"> See also: Galaxy, List of galaxies </Td> </Tr> </Table> <Tr> <Td_colspan="2"> The Milky Way's Galactic Center in the night sky above the Paranal Observatory (the laser creates a guide - star for the telescope). </Td> </Tr>

How many stars in our milky way galaxy