Tip:
Highlight text to annotate it
X
Music
Narrator: Astronomers have just begun imaging planets around other stars
the technique isn't very advanced yet, and it can't see any planets
as small as those in our own solar system. But let's suppose for a moment that alien astronomers
are looking at our planetary system. Could they find any evidence that planets exist
around the sun, even if they couldn't see the planets themselves? The answer
is probably yes. That's because at least one world in our solar system would make its
presence known by its effects on a huge cloud of dust at the fringes of the solar system
in a place called the Kuiper Belt. The Kuiper
Belt is a kind of cold storage zone out beyond Neptune, occupied by millions of
icy bodies, including Pluto. The icy objects in the Kuiper Belt
release dust that from afar, could appear as a hazy disk at infrared wavelengths.
New computer models created by NASA scientists,
shown here, reveal what dust in the Kuiper Belt might look like to an alien astronomer.
Neptune creates the intricate pattern. The massive planet's gravity
tugs on the clouds dust grains, nudging them in their orbits.
Stark: Neptune creates a ring structure in the dust cloud which features a gap where the planet
itself resides. And this gap should make it fairly easy to tell where Neptune is from
afar, even at distances where the planet is too dim to detect directly.
The supercomputer simulations that Marc Kuchner and I performed also
allow us to see what the dust in the solar system may have looked like when the solar system was much
younger. In effect, we can go back in time and see how the distant view of
the solar system may have changed. Narrator: In its youth, the Kuiper Belt
contained many more objects and, consequently, lots more dust. In fact,
the dust was so thick that the particles themselves often collided.
Stark: When we included collisions between dust particles, we were really amazed by what we saw.
Narrator: Successively younger models of the Kuiper
dust cloud show progressively simpler structure, eventually leading to a single
narrow ring beyond Neptune's orbit. Stark: Dust
collisions change Neptune's gravitational imprint. The gap in the ring
disappears.
The amazing thing is, we've already seen ring structures like this around other
younger stars, like Fomalhaut. In terms of
dust, we now know that these other systems may look similar to our young
solar system. Narrator: Dust around other stars can tell
us a lot about possible planets, just as in our own solar system, it could reveal
Neptune. Music
Beeping