# Tag Info

28

With a resolution of 1E-09 radians, Jupiter would be 1 pixel wide at 7 light years. If you had 1E-10 radians, you could resolve the largest features. Visible light has a wavelength of 5E-07 meters, so if you wanted to use a cluster of telescopes to synthesize an aperture with some kind of coherent combination, "all you would need" is a 200 meter diameter ...

26

Kepler has a parabolic dish antenna fixed to its body. There are many possible designs of transmitting devices. For spacecraft, parabolic dish antennas are preferred, because they have the least attenuation for radio waves with distance. But dish antennas must be pointed to the receiver. The Kepler telescope was over-budget for a Discovery-class mission, ...

23

I'm afraid it would be extremely difficult - simply the number of photons reflected off a planet surface and reaching Earth (and the telescope lens, however big) within timeframe for a solid photo is too small to create any meaningful image. Planets are not stationary; they orbit their stars, and that means long-exposure photo will show them as a trails. Of ...

22

I would argue that no specific level of molecular or atomic oxygen in atmosphere is indicative of carbon-based life (i.e. life as we know it on Earth). A planet could have oxygen rich atmosphere which could be due to naturally occurring thermo-chemical reactions (e.g. Sabatier/Bosch reaction), loss of hydrogen in water vapor through atmospheric escape and ...

20

It's not currently possible to get the details of a planet from a distance like a light year or more. Furthermore the projects mentioned below do not aim to get good images of the surface, but only to detect exoplanets, and do basic measurements. The reason is that getting detailed pictures of the surface is beyond current technology capability and research. ...

15

There are incredible, mindboggling distances involved in merely reaching an exoplanet. Alpha Centauri Bb, the closest known exoplanet, is 4.365 light years away. That's 41,295,000,000,000 km (25,660,000,000,000 mi), or 276,000 AU (the distance from the Earth to the Sun). Voyager 1 has left most of our solar system behind and is traveling a blistering 17.3 ...

14

None of the TRAPPIST-1 planets are "considered habitable"; we don't know nearly enough about them to say that (any news article which referred to the planets themselves as "habitable" needs firm correction). Three of them are within the habitable zone of the star, which is defined as the region around the star where liquid water could potentially be found on ...

13

Getting hard numbers about how accurate measures we can get from current systems, adapted to the Sun instead of far away stars is difficult, bordering to impossible. But we can get data about the relative difficulty of the solar system planets. First off, we can do some cheating for Mercury and Venus, as they occasionally go in front of the Sun. Given your ...

13

For Jovian and Saturnine moons, the simplest answer is no, at least not much more habitable than our own Moon is, because none of these moons have their own magnetic field or sufficient mass and their atmosphere would eventually thin out via the ionospheric hydrogen loss due to the solar wind. A bit more difficult answer is how many of these moons would be ...

12

Within 100 light-years, there are approximately 14,600 stars. Many of these are not even known. It is difficult to determine exactly the number of star systems as opposed to stars. 113 star systems within 100 light-years are confirmed to have exoplanets in them (listed from nearest to furthest): Alpha Centauri B → cont'd ↓ → cont'd ↓ ...

12

I would argue that it is disproven already. There have been studies done with Extrasolar planets, and it has been found to only apply in a very small number of instances. There might be some that follow the law, but the number is quite small. There are instances where it lines up nicely, but it seems like ultimately it fails most of the time.

11

Jupiter is about as large as a planet can get, physically. Suppose we slowly add hydrogen and helium to Jupiter, so slowly so as to keep it at more or less its current temperature. Surprisingly, it would get smaller. Jupiter is about as large as a planet can get. (There are exoplanets that are larger than Jupiter, but that's because they orbit so close to ...

10

But I would think an unmanned spacecraft sent for a flyby of an expolanet would be a revolutionary step in this field. Better said: Impossible, at least using anything close to current technology. Getting to Alpha Centauri in 60 years would require an average velocity of nearly 22,000 kilometers per second, or 0.5 astronomical units per hour. That high of ...

9

@SF. is right. It is true that a location far from Earth could have access to different orbital planes and thus potentially see a different set of occultations an transits, you would have to move very very far away from the Earth to make any difference. The same budget and time would be much better spent developing a next generation optical space telescope ...

9

Planets are usually rotating, and so you can't time two passes over a single geographical feature to time an orbit. But you can time successive sunrises to get a good approximation of the orbital period, or some other astronomical coordination between the planet's limb and the celestial sphere. From this answer: Starting with T = 2\pi\sqrt{\frac{a^...

8

The first third of Earth's own existence had neglible atmospheric oxygen. (Simple) life existed during a few hundred million years of this period. Thus, atmospheric oxygen does not correlate with life on a planet.

8

Yes, they are starting to examine exoplanet atmospheres. A spectroscopic analysis is made of the light from a exoplanet transiting its star. The spectra of the star is subtracted from the combined star/planet data, and the remainder is assumed to be the absorption spectra from light passing through the planet's atmosphere. Here's an article from a recent ...

8

From here: The age of the exoplanet is not independently derived, but instead, taken from the age of the host star. So how do they calculate the age of the host star? Wikipedia has a number of methods: As stars grow older, their luminosity increases at an appreciable rate. Given the mass of the star, one can use this rate of increase in luminosity in ...

8

Here is a map of all known exoplanets Go to the link and click in the tight bunch of dots in the upper left - that is the section of sky Kepler is searching. Kepler 186 is at 19h54m37s by 43d57m. Damage due to a micro-meteor in interstellar space is extremely unlikely. Interstellar space is very empty compared to a solar system. Even passing through the ...

8

The best method of analyzing exoplanet atmospheres is called Transit Absorption Spectroscopy. First, we analyze the spectrum of an exoplanet's star. Then, we wait for the planet to pass in front of the star. When it does so, some of the star's light is absorbed by the planet's atmosphere, changing its spectrum. Analyzing this change will tell us what ...

8

The temperature estimate is based on no atmosphere. For instance, Earth, without our atmosphere, would have an average temperature of -20°C . The equator should be warmer, and any atmosphere will also add heat. Also, the objects are most likely tidally locked, which means that a single side of the planet will always face it's star, making it even warmer in ...

8

So the main thing of interest in this post seems to be angular resolution. You're after objects that are relatively bright and small. Angular resolution increases linearly with aperture size. However, you don't necessarily need a giant light-bucket of a telescope to achieve high resolution. You can achieve some impressive resolution through use of ...

7

The most feasible that I've seen, which isn't all that high on the feasibility scale, is a very large, very low mass wire mesh containing sensors that is accelerated and powered by a microwave beam from Earth. See Starwisp.

7

YES Ok, it is easy to say yes but the basic idea is statistics. There are more and more planets discovered outside of our solar system virtually every day. With better instruments, ever smaller planets can be discovered. Besides, it depends on your definition of 'earth-like'. If you restrict this to size, the distance to its star (with respect to the '...

7

As @TidalWave said, no specific level of oxygen is by itself sufficient to potentially indicate life. However, based on this article, what astronomers are looking for is the combination of both oxygen and methane in a single atmosphere. Both oxygen and methane can be created independently by nonliving processes, so their individual presence is of ...

7

Why would Kepler rotate towards Earth instead having an antenna always directed to Earth? There was no need to always have an antenna pointed directly at the Earth because communication with the Earth was infrequent, less than eight hours per month. There are a lot more deep space assets than there are receivers to communicate with those assets. The ...

7

Detecting chlorophyl on exoplanets is definitely something people are interested in: see this paper (published as "Detecting biomarkers on an exo-Earth", Timothy D. Brandt, David S. Spiegel, Proceedings of the National Academy of Sciences Sep 2014, 111 (37) 13278-13283; DOI: 10.1073/pnas.1407296111), for instance. On the assumption that people are writing ...

6

The answer is strongly defined by how one defines "Earth Like." The working definition has yet to be established for the scientific purposes that I've seen. The common minimum: terrestrial, within the liquid water zone, and not more than about 4 Earth masses; a lower bound of about 1/2000th Earth mass (large enough to be self rounding). In which case, ...

6

There are several problems with that idea: As mentioned by uhoh and SF, reaching a point far enough away from our solar system to make a different observation than Kepler's takes so much time, that the telescope and the data will in fact be antiquated by the time they reach that point - even IF (and that's a very very big IF) we could even manage to build ...

6

Two planets sharing their orbit is expected to be a rare configuration. Most configurations of 2 planets in 1 orbit are unstable. Only when one planet is in a Lagrange point of the other, are the orbits stable. As of now (February 2017), there are no known co-orbital planets. We do know lots of smaller objects co-orbiting with planets (in our own solar ...

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