Tycho Brahe (Martian crater) Tycho Brahe (Martian crater) Tycho Brahe is a nearly ovular crater on Mars named after the Danish astronomer Tycho Brahe (1546–1601). It is located in the Cerberus hemisphere around 49.8° south and 213.9° west, in an area which is south of the Martz crater and east of the Hellas Basin. It measures approximately 105 kilometers in diameter from east to west. The name was adopted by IAU's Working Group for Planetary System Nomenclature in 1973. The crater is crossed by Eridania Scopulus, an escarpment. Other nearby named craters are Huggins to the east, far south is Vinogradsky and northwest is
Planetary nebula possible to determine distances to the nearest planetary nebula by measuring their expansion rates. High resolution observations taken several years apart will show the expansion of the nebula perpendicular to the line of sight, while spectroscopic observations of the Doppler shift will reveal the velocity of expansion in the line of sight. Comparing the angular expansion with the derived velocity of expansion will reveal the distance to the nebula. The issue of how such a diverse range of nebular shapes can be produced is a debatable topic. It is theorised that interactions between material moving away from the star at