Seyfert galaxies are____
a. spiral galaxies with unusually luminous nuclei
b. elliptical galaxies with very broad emission lines
c. explained by the double-exhaust model
d. extremely luminous objects with high redshifts only
e. glowing green gases due to excitation from energy from an active core
a
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Pluto's density is 1.8 g/cm3 . Iron is about 5 g/cm3 . Rock is about is 3 g/cm3 . Ice or water is 1.0 g/cm3 . . This implies that
a. Pluto has a large iron-nickel core. b. Pluto is about 50% water and 50% rocky material. c. Pluto is all rock. d. Pluto is all water or water ice.
Earth's rotation axis ____________________ slowly so that in a few thousand years Polaris will no longer be the North Star
Fill in the blank(s) with correct word
Which of these were observed from Earth, prior to spacecraft missions to Mars?
A) seasonal changes in the polar caps B) eruptions of Mount Olympus C) dust storms capable of covering the entire planet D) Both A and C are correct. E) All of the above are correct.
Two long straight wires carry currents perpendicular to the xy plane. One carries a current of 50 A and passes through the point x = 5.0 cm on the x axis. The second wire has a current of 80 A and passes through the point y = 4.0 cm on the y axis. What is the magnitude of the resulting magnetic field at the origin?
a. 200 mT b. 600 mT c. 450 mT d. 300 mT e. 400 mT