Examlex
The Hipparcos mission's observations have given us good data on stars out to about:
Q18: The temperature inside an H II region
Q21: What natural barrier tries to prevent two
Q22: The Oort Cloud is thought to be:<br>A)
Q24: What do X-ray observations tell us about
Q41: The H I regions are mapped by
Q51: The "wispy terrain" on Rhea was revealed
Q64: Why were the mass and density of
Q67: Although the atmospheres of Uranus and Neptune
Q70: Explain how the shifting spectral lines of
Q90: The energy of the Sun starts as