- 4383
- KUIPER BELT
- and other planet atmospheres? -
The Kuiper Belt which is the comets and subplanets just past Pluto is
much bigger than we thought. The “New
Horizons” spacecraft is just over 8.8 billion kilometers away, exploring the
outer reaches of our solar system.. This icy belt surrounds the Sun but it
seems to have a surprise up its sleeve.
-
------------------- 4383
- KUIPER BELT
- and other planet atmospheres?
-
- It was expected that “New Horizons” would be
leaving the region by now but it seems that it had detected elevated levels of
dust that are thought to be from micrometeorite impacts within the belt. It
suggests perhaps that the Kuiper Belt may stretch further from the Sun than we
thought!
-
- The Kuiper Belt is found beyond the orbit of
Neptune and is thought to extend out to around 8 billion km. Its existence was
first proposed in the mid-20th century by Gerard Kuiper after whom the belt has
been named. It’s home to numerous icy
bodies and dwarf planets and offers valuable insight into the formation and
evolution of the Solar System.
-
- Launched by NASA in January 2006 atop an
Atlas V rocket, the New Horizon’s spacecraft embarked on its mission to explore
the outer Solar System. The primary objective was to perform a close flyby of
Pluto, which it did 9.5 years after it launched, and continue on to explore the
Kuiper Belt.
-
- New Horizons completed its flyby of Pluto in
2015. As it travels through the outer
reaches of the region, almost 60 times the distance from Earth to the Sun, it
has been counting dust levels.
Throughout New Horizon’s journey it has been monitoring dust levels
giving fabulous insight into collision rates among objects in the outer Solar
System.
-
- The dust particle detections are thought to
be frozen remains from collisions between larger Kuiper Belt Objects (KBOs).
The results were a real surprise and challenged the existing models that
predicted a decline in dust density and KBO population. It seems that the belt
extends many billions of miles beyond the current estimates or maybe even that
there is a second belt!
-
- The results came from data gathered over a
three year period during New Horizon’s journey from 45 to 55 astronomical units
(where 1 AU is the average distance between the Sun and Earth).
-
- While New Horizon’s was gathering data
about dust, observatories such as the 8.2-meter optical-infrared Subaru
Telescope in Hawaii have been making discoveries of new KBOs. Together these findings suggest the Kuiper
Belt objects and dust may well extend a further 30 AUs out to about 80 AUs from
the Sun.
-
- New Horizons is now in its extended mission
and hopefully has sufficient power and propellant to continue well into the
2040s. At its current velocity that will take the spacecraft out to about 100
AU from the Sun so the research team speculate that the SDC could identify the
transition point into interstellar space.
-
- Studying planetary atmospheres can teach us
about finding life beyond Earth. We
think the sun was much dimmer in the early history of the solar system, yet
Earth and Mars each were as warm or warmer than now. How is this possible?
Venus and Mars have carbon dioxide dominated atmospheres with more CO2 in the
vertical column than Earth. Yet one is colder than Earth and the other warmer.
-
- Even though Venus is closer to the sun its
clouds reflect so much light that it effectively has less sunlight than Earth,
yet its surface is warm enough to melt lead. How is this possible? We need to
understand other atmospheres to understand the past and future of Earth.
-
- Aside from Earth, Venus, and Mars, the
other planetary bodies in our solar system that possess atmospheres include
Jupiter, Saturn, Uranus, Neptune, dwarf planet Pluto, and Saturn’s largest
moon, Titan, which is the only solar system moon with a dense atmosphere. The
formation and evolution of these atmospheres are what scientists are attempting
to better understand via computer models that are often combined with data
obtained by ground- or space-based telescopes.
-
- Scientists continue to learn, a great deal
about the atmospheres of these intriguing and mysterious worlds that inhabit
our solar system. But even with all the instruments and technological
advancements, what are some of the benefits and challenges of studying
planetary atmospheres?
-
- The same climate models used for Earth are
now used for other planets. When the
models fail on Earth it is tempting to force them to match Earth data rather
than fixing the physics and chemistry in the models. Having the examples from
other planets force us to look for errors in Earth models or in our
understanding of how Earth climate models work.
-
- Planetary atmospheres within our own solar
system range from sulfuric acid and carbon dioxide (Venus) to carbon dioxide
(Mars) to hydrogen and helium (Jupiter, Saturn, Uranus, and Neptune) to
nitrogen and methane (Titan and Pluto).
-
- Despite the sulfuric acid within Venus’
atmosphere, past studies have postulated the possibility of Venus’ higher
altitudes potentially having the ingredients to support life as we know it.
Therefore, these unique worlds could offer a glimpse of what scientists could
find beyond our solar system, known as exoplanets.
-
- We expect a wide range of exoplanetary
atmospheres, some are so hot that they likely are raining metals. Even in the
solar system there are planets raining condensed natural gas. So, the solar
system planets are analogs for exoplanets, but there are definitely exoplanets
very different from solar system planets.
-
- Since the distance to exoplanets ranges
from a few light-years to hundreds of light-years, it takes extremely powerful
instruments to study their atmospheres.
JWST has examined the atmospheres of several exoplanets, including
“WASP-39 b”, which is located just under 700 light-years from Earth.
-
- With its powerful infrared instruments,
JWST successfully identified water, carbon dioxide, and potassium on this
Jupiter-sized world. Water is essential
for life as we know it. Therefore, finding water on an exoplanet could indicate
its likelihood for life, as well.
-
- However, out of the almost 5,600 confirmed
exoplanets as of this writing, only 69 are deemed potentially habitable. This
is primarily due to their orbit residing within their star’s habitable zone
(HZ), meaning they orbit at the correct distance from their star for liquid
water to potentially exist on its surface, assuming the exoplanet is
terrestrial (rocky) like Earth.
-
- The oxygen in Earth’s atmosphere is not
compatible with the methane in the atmosphere. The methane is largely a waste
product of life. So, trying to detect life elsewhere is most likely going to
start with looking at the chemistry of exoplanet atmospheres for signs of
chemical imbalance.
-
- The planetary atmospheres within our solar
system provide a wide range of diversity and scientists have observed the same
diversity on exoplanets. There is a lot
of data for Mars, and Mars once had a climate more like Earth’s than the barren
desert it is now.
-
- Titan, a moon of Saturn is also interesting
because it has methane rain, and lakes and seas of hydrocarbons. It also is
shrouded in a haze composed of complex organic material. It is surprising how many astronomers
looking at planetary atmospheres don’t know about parallels with Earth.
-
- How will planetary atmospheres help us
better understand our place in the universe in the coming years and decades?
Only time will tell, and this is why we science!
-
-
March 9, 2024 KUIPER
BELT - and other planet atmospheres? 4383
------------------------------------------------------------------------------------------
- Comments appreciated and
Pass it on to whomever is interested. --------
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for
copies or Index of all reviews
--- to:
------
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------ “Jim Detrick” -----------
--------------------- --- Sunday, March 10, 2024
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