Webb and the Solar System

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This true-color picture of Mars (left) shows what the human eye would see. The false-color infrared image (right) reveals features that could not be seen in visible light, including variations in the abundance and distribution of water-bearing minerals.
When we think of our solar system — the Sun and the planets and minor bodies that orbit it — we think of it as it appears in visible light. But there are better ways to see it. Visible light is simply the Sun's light reflected off objects like planets, moons, and asteroids. To see these objects' intrinsic glow, we must look at infrared light.

Examining planetary systems and the origin of life is one of Webb's core goals. The infrared telescope will observe Mars and the giant planets, dwarf planets like Pluto and Eris, and even the small bodies in our solar system: asteroids, comets, and Kuiper Belt objects. Webb's unprecedented improvements in sensitivity and resolution provides it with the ability to resolve small features on planets, and precisely analyze the light from objects in our own backyard.

Our Closest Neighbors

Turning its gaze on our rocky inner planets, Webb will help us to understand Mars' atmosphere, and conduct studies that verify findings of the Mars rovers and landers. The presence of water on Mars now and in the past is one of the driving forces for Martian exploration. Does the atmosphere of Mars reveal a more habitable past? Is it habitable now? Are there unidentified sources of water on Mars? How wet was — or is — Mars? What processes altered the stability of its atmosphere? Besides searching for water, geologists will use Webb to study the formation and evolution of global dust storms and cloud systems over dormant volcanoes, and search for traces of chemical changes in the atmosphere.

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Outer Planets

Looking farther, into the outer solar system, Webb's observations will give us a better picture of the seasonal weather and climate on our giant planets and their moons. For instance, Webb will be an important tool for keeping track of the changing seasons on Saturn's moon Titan. Saturn's long orbit around the Sun means its seasons change slowly over the course of 29.5 Earth years. Webb will reveal the interplay of chemistry and atmospheric dynamics in response to the shift of Titan's seasons. To probe Titan's complex chemistry, Webb will investigate the composition of the atmosphere, watch clouds, track hazes, and monitor changes on the surface that occur with precipitation, geologic activity, or sea shrinkage.

Webb also offers unprecedented observing opportunities in near- and mid-infrared wavelengths for Jupiter, Saturn, Uranus, and Neptune. Potential groundbreaking investigations of these planets include studies of how their aurorae emerge, tracking atmospheric changes in the aftermath of comet or meteor strikes, and more. Webb's infrared capabilities can be used to probe different depths in these atmospheres, mapping cloud structures and major storm systems, as well as their evolution, with finer detail than previously possible.

Webb will enable mapping of organic molecules — called hydrocarbons — across the disks of Uranus and Neptune for the first time, providing insight into the thermodynamics, chemistry, and circulation within these two atmospheres. These investigations will reveal whether such changes are consequences of seasons, local weather, or solar activity.

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This artist's impression shows a Kuiper Belt object located on the outer rim of our solar system, about 4 billion miles from the Sun. Pluto is a Kuiper Belt object, as are many comets.

Small Wonders

Finally, asteroids and other small bodies in our solar system possess features that Earth-based observatories are blind to, but that Webb will be able to identify by analyzing those objects' light. Webb will also help us learn more about the composition and mineralogy of these rocky objects.

Updated: May 10, 2016