Astronomy - February 2014

WWW.ASTRONOMY.COM 35

Physicists believe that the
simplest explanation of a
scientific question is often the
best, so we conclude that
throughout the universe, when
matter collides with antimatter,
the interaction produces the
same energy we see on Earth. If
the laws of physics are constant
over time, we assert that when
the cosmos was full of matter
and antimatter, starting around
one-trillionth of a second after
the Big Bang, collisions between
them produced the same energy
we see and feel every day.
As the universe expanded
and cooled, the collisions’
energy went right back to where
it came from: matter, antimatter,
and energy. For some reason,
however, there was one slight
asymmetry; the process created
more matter than antimatter,
which is why we see only matter
today. The early universe’s anti-
matter and matter simply con-
verted into our matter. Thank
goodness, too — an astronaut
would not want to meet up with
antimatter debris.
Howard Matis
Lawrence Berkeley National
Laboratory, California

Q: Do the gas giant
planets have Discern-
ible surfaces? if so,
woulD they support
objects?
Al Kuyper
Clive, Iowa

A: Gas giants like Jupiter and
Saturn do not have solid sur-
faces in the sense that if you
dropped in a penny, it would
never land with a “clink.” These
bodies are mostly composed of
hydrogen at temperatures above
the “critical point” for hydro-
gen, meaning there is no sharp
boundary between solid, liquid,
and gas regions.
But gas giants do have lay-
ers. For example, if you could
somehow endure the high

temperatures, pressures, and

radiation levels and survive a

dive into Jupiter, you would first

swim through a stormy atmo-

sphere of hydrogen. You would

pass through layers of ammonia

clouds, sulfide clouds, and then

water clouds. You would proba-

bly even begin to float when the

density of the gas around you

matched that of your body.

But if you could weigh

yourself down, you could keep

sinking and enter a thick layer

of metallic hydrogen, where

electrons and protons move

separately from one another.

The temperature would get hot-

ter and hotter as you kept diving

— up to about 20,000 kelvins

(35,000° Fahrenheit).

Finally, in Jupiter’s core, the

metallic hydrogen would give

way to heavier elements like

silicon and iron. Here, your

body, crushed to ½5 its size and

stripped of most of its electrons,

would probably rest forever.

Marc Kuchner

NASA’s Goddard Space Flight Center,

Greenbelt, Maryland

Q: why is one of the

three filters in the

hubble palette ionizeD

sulfur? is sulfur really

that prevalent in the

universe?

Dennis Demcheck

Baton Rouge, Louisiana

A: Sulfur is not terribly abun-

dant in the universe. It shows

up, however, near high-energy

regions and objects such as

supernova shock fronts and hot

massive stars.

We typically see this element

near areas where high-speed

gases are colliding. The gaseous

remains of exploded stars —

called supernova remnants —

tend to have relatively strong

sulfur emission. We also see it

in the gas ejected from dying

Sun-like stars and their rem-

nants, planetary nebulae. Hot

young stars emit ultraviolet

light, which kicks electrons off

nearby atoms, thus ionizing

them. Sulfur is one of the ion-

ized gases we see near these

young suns. Sulfur is useful to

astronomers as a diagnostic tool

that shows us where shocked

gases and high amounts of

ultraviolet radiation are.

Thus, to capture images of

such regions, the Hubble Space

Telescope’s Wide Field Plan-

etary Camera 2 (1993–2009)

included a narrowband sulfur

filter. This filter let only a small

range of light around a wave-

length of 672 nanometers pass

through to the camera.

Howard E. Bond

Pennsylvania State University,

University Park

send us your

questions

Send your astronomy

questions via email to

[email protected],

or write to Ask Astro,

P. O. Box 1612, Waukesha,

WI 53187. Be sure to tell us

your full name and where

you live. Unfortunately, we

cannot answer all questions

submitted.

The Soul Nebula (Sharpless 2–199) contains open clusters with young stars. The hot forming suns emit ultraviolet

energy, ionizing nearby sulfur atoms. The photographer processed this image so that the sulfur gas glows red, while

hydrogen shows up as green and oxygen as blue. BOB FRANKE