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Bell Tone

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Music

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Although we can't feel it,

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our solar system is constantly being changed by a galactic wind.

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The wind is composed of gases like hydrogen, helium, oxygen and

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neon, which form a very wispy "atmosphere" between stars.

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This gas is called the interstellar medium. Like a bicycle

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traveling in a crosswind, the wind that the solar system feels is actually a

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combination of a solar system's movement relative to the galaxy and the

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movement of the interstellar medium itself. The solar wind

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pushes out against this galactic wind, forming a bubble called the heliosphere.

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The outer boundary is called the heliopause, and is blown

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into a teardrop-shape by the galactic wind. IBEX, or the

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Interstellar Boundary Explorer is designed to study this region from Earth

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orbit and has now made the first direct measurements of hydrogen,

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oxygen and neon from outside the solar system.

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Many instruments have seen the characteristic spectra of elements outside the solar

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system, but IBEX is actually detecting atoms from interstellar

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space that punch through the heliopause and strike the spacecraft.

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Only some of the atoms that make up the galactic wind can do this.

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Much of the galactic wind is made up of

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ions, which are atoms with charge due to missing electrons.

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the remaining atoms are neutral; they have the same number of electrons and protons.

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The ions are deflected by the magnetic field of the sun,

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just like the magnetic field of the Earth deflects the solar wind, but the

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neutral atoms are unaffected and go straight through.

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The measurement of these atoms by IBEX has enabled scientists to get a better

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grasp on the environment around our solar system.

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The speed of the galactic wind registered around 52,000 miles per hour,

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which is about 12% slower than previously thought. At that speed,

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it still takes about 30 years for each atom to reach

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IBEX from the edge of the solar system. The IBEX measurements

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of heavy interstellar atoms, oxygen and neon, show a

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difference from the solar system and galaxy as a whole. This puzzle

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may mean that the sun has moved out of the region where it formed, or that some

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of the oxygen has been captured by dust in interstellar space.

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These direct, physical measurements of the universe right on the sun's

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doorstep help us understand the history and future of our solar system

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and the galaxy. What scientists learn can help protect

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human spaceflight and teach us more about our home in the Milky Way.

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Music