Discover Questions

How do we know if any other planets have oxygen in the atmosphere? I need help with the above question. Please show steps and final answers. Thanks!!!? Going the speed of light how long will it take to get to the next “earthlike” planet? Very difficult question, try hard to answer it. Which do you prefer: a waning moon or a waxing moon and why? Tina has 20 rings. In how many ways can she select a set of 3 rings?
A.) 1140
B.) 1000
C.) 950
D.) 850?