Protostars are difficult to observe because
a. the protostar stage is very short.
b. they are surrounded by cocoons of gas and dust.
c. they radiate mainly in the infrared.
d. the protostar stage is very short, they are surrounded by cocoons of gas and dust, and they radiate mainly in the infrared.
e. they are all so far away that the light hasn't reached us yet.
Ans: d. the protostar stage is very short, they are surrounded by cocoons of gas and dust, and they radiate mainly in the infrared.
You might also like to view...
Ashen light (or earthshine) is
A) sunlight reflected by Earth that illuminates the "dark" portion of the Moon. B) the sunlight that shines on the face of the Moon that we never see. C) the light from the Moon that illuminates Earth's surface at night. D) the light we see at dawn just before the Sun rises. E) the light we see at dusk just after the Sun sets.
Astronomers can determine the mass of Jupiter by the gravitational pull Jupiter exerts on its moons.
Answer the following statement true (T) or false (F)
A hot air balloon along with its cargo has a mass of 4.0 x 105 kg, and it holds 7.0 x 105 m3 of hot air. It is floating at a constant height in air with a density of 1.29 kg/m3. What is the density of the hot air in the balloon?
A) 1.4 kg/m3 B) 0.72 kg/m3 C) 0.57 kg/m3 D) 0.86 kg/m3 E) 0.43 kg/m3
Fission and fusion reactions have in common _______
a. absorption of energy in the nuclear reaction b. high temperature requirements c. liberation of neutrons d. loss of mass of products over reactants e. gain in mass of products over reactants.