Which of the following layers of the Earth is unique among the terrestrial planets?
A) hydrosphere
B) ionosphere
C) mantle
D) crust
E) core
Question 2
What are constellations?
A) groups of galaxies gravitationally bound and close together in the sky
B) groups of stars making an apparent pattern in the celestial sphere
C) groups of stars gravitationally bound and appearing close together in the sky
D) ancient story boards, useless to modern astronomers
E) apparent groupings of stars and planets visible on a given evening
Unique markings identify individual humpback whales.
The Sun as it appears from the surface of the Earth at Sunset.
Dwarf Planets
Comparison of Ceres with the Moon and Earth
Earth’s Biomes "الأرض الحيوية"
Earth Present