New answers tagged

1

The answer is no. There are no resolved images at any wavelength of black holes or black hole candidates that demonstrate their lensing effect. There are of course lensing images due to massive objects that probably have black holes at their centres (e.g. Courbin et al. 2010 and see below), but that is not the same thing. A quasar acting as a ...


1

This is my first post, and I've accidentally deleted almost all I've written! a later edit with an answer The RA of a culminating star gives you the local sidereal time and comparison with Greenwich Sidereal Time gives your local longitude by noting the difference between the two. If local sidereal time is less than Greenwich, your position is west of ...


6

It's unlikely that either Mercury or Venus could have moons to begin with. Both of these planets are pretty close to the Sun — and in general, this prevents moons from finding stable orbits. If a moon were too close to the planets, it would fall within the Roche limit and be torn apart by tidal forces. If a moon were too far from the planets, it would fall ...


2

What they have at present is best described as a theory based on data that is not precise enough to make a definitive statement. They are telling people they think something is out there and roughly what they think it might be, but they really don't have accurate enough data to make any statements beyond that. The fact that the possible range of distances ...


25

Brown and Batygin, the authors of the paper on the possible planet, have a webpage addressing this. A few reasons not already covered: It moves quite slowly - the authors estimate 0.2-0.6 arc seconds per hour - so standard surveys may not notice the movement and fail to recognize it as a solar system object. Eris, which is the most distant confirmed ...


5

The clipping above from the Albuquerque Journal doesn't really answer your question, but astronomers have been hunting for a largeish planet beyond Pluto for quite some time now. See also: http://www.zetatalk.com/theword/tword26b.htm http://www.bibliotecapleyades.net/hercolobus/esp_hercolobus_2_02.htm (under "United States Naval Observatory ...


7

Possible reasons that the planet has not been picked up previously: It's not there. Photographic proper motion surveys cover the whoke sky. To avoid these planet 9 would have to be fainter than about 18th or 19th magnitude. This puts a lower bound in the size/albedo/distance combination for any planet 9. The proposed planet could easily be fainter than ...


16

There are many normal methods that we use to detect exoplanets, but none of them work well in the case of the 9th planet. Here are some of the main ones. Radial velocity. The Sun is not moving significantly with respect to Earth, and the hypothetical planet is too far away from the Sun to have much of an impact. Transit. This is obviously impossible, as ...


18

This graph from XKCD says a lot about why that is the case The bottom line is, the 9th planet is too small to be detected through WISE, and too far/small to have been detected through visible observation. Most likely this hypothetical planet is a long ways away, possibly as far as 1200 AU, and not particularly large, making it difficult to see. WISE was ...


6

There are two basic ways to detect such an object. First is to detect it through reflected sunlight. Second is from the heat that it produces. We already know that the reflected light of such an object likely would be around a 16.5 magnitude. To determine the infrared, we have to estimate the temperature The temperature very much depends on the composition. ...


4

Direct reflection of sunlight is the most likely scenario for a ninth planet discovery, however that does not hold if the object has a very low albedo. I assume you are interested in what wavelengths the planet would radiate. For the surface temperature, the rotation of the planet is important. If it is locked with one side facing the sun, or rotates very ...


8

The possible planet 9 is thought to be about 10 Earth masses and is unlikely to be a gas giant (it may be the core of an "interrupted" gas giant). As such, it will not be generating significant luminosity itself and would be rocky, or more likely, icy in character. It would thus only be seen by reflected light. The considerations for what wavelength to ...


3

Maybe the Gaia space telescope has already caught it? First data release in mid-2016.


8

Those are model calculations, which hint to the existence of a possible body of about 10-times the mass of Earth. Calling this a discovery would clearly be premature. The confidence level is just a little above the "evidence" level of 3 sigma, under the assumption, that the discoveries of the KBO objects leading to the inference aren't observationally ...



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