"Solar wind" is the term scientists use to describe the stream of particles that the sun's corona constantly emits. These solar winds, which consist mainly of hydrogen and helium, are intensely hot, fully ionized plasma. Because of the corona's intense heat, these particles continuously escape the sun's gravitational attraction, flowing away from the sun at extreme velocities. Solar winds, though, are not without variation, because they contain faster and slower moving pockets. For instance, solar winds that originate from streamers are slower moving winds at approximately 300 km/second, as opposed to the winds that originate from corona holes and reach speeds of 800 km/second. As they flow away from the sun, tangential discontinuities and interplanetary shocks form, producing pressure variations. Moreover, researchers also know that solar winds are directly related to geomagnetic storms, auroras, and comets. It is these winds that cause comet tails to bend away from the sun, as Kepler accurately predicted in the early 1600s.

Studies have been done on the effect of solar winds on the planets in the solar system. While all the planets are surrounded by this hot, super-charged plasma, the Earth's magnetic field protects it from the solar wind by deflecting the particles. However, solar winds are responsible for the Earth's magnetosphere, and changes in their speed and direction strongly influence Earth's space environment. As the planet closest to the sun, Mercury endures the main impact of solar winds. If Mercury had an atmosphere, these winds would have stripped it away, leaving the planet bathed in radiation. Though Mars is much further from the sun than Mercury, solar winds have also greatly reduced its atmosphere. While Venus has a substantial atmosphere-100 times denser than ours — solar winds reduce its clouds. It is not just those planets nearest the sun which bear the effects of solar winds: The winds
travel far beyond the limits of Pluto. Inter-estingly, while much is now known about solar winds, scientists still do not fully understand how the gases and particles in the sun's corona reach such high velocities.

Consider each of the following answer choices separately and select all that apply.

According to the passage, which of the following is true of the effect of solar winds on the Earth?

A. Though the Earth’s magnetic field largely protects it from the full effects of solar winds, the winds have an impact on its magnetosphere and its space environment.
B. Solar winds play a significant role in the development of auroras and geomagnetic storms in the earth’s space environment.
C. Because of the corona’s intense heat, solar wind particles continuously escape the sun’s gravitational attraction, flowing away from the corona at extremely high velocities and surrounding the Earth with hot, super-charged plasma.



It can be inferred from the passage that the Earth’s magnetic field acts to

A. absorb the particles blown by solar winds
B. incinerate the particles present in solar winds
C. assimilate the particles in solar winds into the Earth’s atmosphere
D. divert the particles in solar winds from the Earth
E. re-orient the particles in solar winds toward a central collection point



The author most likely discussesKepler’s predictions in order to

A. illustrate the observable effect solar winds have had on other celestial objects
B. denounce Kepler’s work as unreliable because the technology required to study solar winds directly has only been developed within the last century
C. describe more generally the first major contribution to the study of solar winds and the sun
D. disprove Kepler’s theories on the motion of comets and auroras
E. establish a standard against which to compare the observations concerning the atmospheres of Mars and Mercury



Select the sentence that attempts to correct a possible misconception about the effects of solar winds.