Henrietta Leavitt discovered the period-luminosity relationship for ____________________
Fill in the blank(s) with correct word
Cepheid variables
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Contrast the difficulty in contacting extraterrestrial life using space flight and radio communication. How might each be done? What are the advantages and limitations of each?
What will be an ideal response?
The mass of an atom of carbon-12 (Z = 6) is less than the mass of 6 protons and 6 neutrons because of __________
Fill in the blank(s) with correct word
The fundamental source of energy released by a tropical hurricane comes from
A) the trade winds. B) the Sun. C) warm moist air. D) the convergence of maritime polar and maritime tropical air masses.
How did Mr. Hubble calculate the age of the universe?
A) by measuring the rate of expansion of the universe B) by looking at the age of the oldest stars C) by measuring the redshift of stars within 360 degrees of the center of our galaxy D) by measuring the rate of radioactive decay within the farthest galaxies