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Mapping Earth-like planets at a distance of 30 lightyears
| Content Provider | Semantic Scholar |
|---|---|
| Author | Oakley, Phil |
| Copyright Year | 2008 |
| Abstract | To date, more than 200 planets have been discovered outside our own solar system.1 Most of these predominantly large, lifeless, Jupiter-like ‘exoplanets’ were found indirectly through their gravitational effects on their host star. However, direct imaging of habitable Earth-like planets in particular is highly desired in our search for life in the universe. Unfortunately, imaging terrestrial planets is extremely challenging because they are ∼10 billion times dimmer than their host stars. Any detector would therefore immediately lose the planet in the intense glare of the star. A promising approach aimed at avoiding this limitation is the development of the New Worlds Observer (NWO).2–4 This mission will use a specially shaped occulter, known as a starshade, to block direct starlight while allowing reflected planetary light to pass unimpeded. Figure 1 shows a simulated NWO image of the Sun–Earth system at a distance of 30 lightyears. Once a terrestrial planet has been discovered, its orbital parameters, temperature, and atmospheric composition will be determined for comparison with the equivalent properties of our own planet. This will hopefully result in the discovery of a ‘sister’ Earth. However, even with this data we still lack critical information about the object’s nature. Is there liquid water on its surface? What are the main surface features? How long does a day last (i.e., how fast does it rotate)? Because of its distance the planet will appear as an unresolved ‘pale blue dot.’ Nevertheless, we can search for biosignatures (e.g., oxygen or water) in its atmosphere. If the surface is characterized by different albedos (e.g., highly reflective snow versus dimmer soil), the overall brightness will vary as continents and oceans rotate through their daily cycle and reflect the starlight, thus allowing us to infer information about these surface features without actually seeing them. Modeling such brightness variations, a fairly recent development,5–7 involves creating a planetary model with realistic terFigure 1. Simulated New Worlds Observer image of an Earth-like planet at a distance of 30 lightyears. The white ring is dust in the stellar system, reflecting starlight under an angle of 30◦. The central black disk is the shadow cast by the starshade. The Earth-like planet is the object with the familiar blue hue. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://spie.org/documents/Newsroom/Imported/1291/1291_4506_0_2008-09-16.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Detectors GUCY2C protein, human Inference Methylene blue Molecular orbital Oxygen Planetary scanner Stars, Celestial Stellar (payment network) Terrestrial television brightness |
| Content Type | Text |
| Resource Type | Article |
