<Table> C / 1995 O1 (Hale--Bopp) <Tr> <Td_colspan="2"> Comet Hale--Bopp, shortly after passing perihelion in April 1997 . </Td> </Tr> <Tr> <Th_colspan="2"> Discovery </Th> </Tr> <Tr> <Th> Discovered by </Th> <Td> Alan Hale Thomas Bopp </Td> </Tr> <Tr> <Th> Discovery date </Th> <Td> July 23, 1995 </Td> </Tr> <Tr> <Th> Alternative designations </Th> <Td> The Great Comet of 1997, C / 1995 O1 </Td> </Tr> <Tr> <Th_colspan="2"> Orbital characteristics </Th> </Tr> <Tr> <Th> Epoch </Th> <Td> 2450460.5 </Td> </Tr> <Tr> <Th> Aphelion </Th> <Td> 370.8 AU </Td> </Tr> <Tr> <Th> Perihelion </Th> <Td> 0.914 AU </Td> </Tr> <Tr> <Th> Semi-major axis </Th> <Td> 186 AU </Td> </Tr> <Tr> <Th> Eccentricity </Th> <Td> 0.995086 </Td> </Tr> <Tr> <Th> Orbital period </Th> <Td> 2520--2533 yr (Barycentric 2391 yr) </Td> </Tr> <Tr> <Th> Inclination </Th> <Td> 89.4 ° </Td> </Tr> <Tr> <Th> </Th> <Td> 40--80 km </Td> </Tr> <Tr> <Th> Nucleus albedo </Th> <Td> 0.01--0.07 </Td> </Tr> <Tr> <Th> Last perihelion </Th> <Td> April 1, 1997 </Td> </Tr> <Tr> <Th> Next perihelion </Th> <Td> 4385 ± 2.0 AD </Td> </Tr> </Table> <Tr> <Td_colspan="2"> Comet Hale--Bopp, shortly after passing perihelion in April 1997 . </Td> </Tr>

When was the last time a comet passed earth
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