Trojan called asteroids that are in the vicinity of the Lagrange points L4 and L5 this or that planet. With planets in orbits which they live, such asteroids form an equilateral triangle. Most such bodies Jupiter, although there are some in Neptune, Mars and Earth. The mystery of their origin scietists.

NASA attempted in-depth study of the asteroids using the infrared space telescope's Wide-field Infrared Survey Explorer (WISE), but the new observations rather added questions.

One part of Trojans "catching up"and the other "is ahead of" Jupiter in its orbit around the Sun ("Trojan horses" and "the Greeks" respectively). But maroon color gives the common origin of both. (Here and below illustrate NASA / JPL-Caltech.)
One part of Trojans "catching up"and the other "is ahead of" Jupiter in its orbit around the Sun ("Trojan horses" and "the Greeks" respectively). But maroon color gives the common origin of both. (Here and below illustrate NASA / JPL-Caltech.)

"Having the exact values of the diameters and surface albedo 1 750 "Trojan" Jupiter, we have increased appreciably our knowledge about these two groups of asteroids ["Trojan" and "the Greeks"], " says Thomas Grew from the Institute of planetology (Arizona, USA). - With this information we were able to more accurately than ever, confirm that in the main cloud their 40% more than previously thought".

Using WISE researchers have carefully studied the color of asteroids both groups. Managed to establish that almost all of the Trojan asteroids are composed of dark, reddish rocks with low reflectivity. Recall that earlier this question was the subject of great debate: from albedo main mass of the "Trojan" Jupiter depend on assessment of their total number (called the numbers up to a million) and weight (up to 20% of the mass of the asteroid belt). If their albedo little, faithful should be considered as the upper estimate (number and weight). These are the findings, say astronomers, and pushing us new data in color and albedo investigated WISE "Trojans". This sharply distinguishes them from the asteroid belt located between Mars and Jupiter, and related to the Kuiper belt beyond Neptune.

"We did not see any infrared asteroids, typical for the main zone and the population of the Kuiper belt, " commented Mr. Grew. - Instead, we found mainly homogeneous population of what we call asteroids D-type, maroon in colour, and among others - rather grey-blue S-and P-types".

And this gives rise to the problem. With the asteroid belt all clear (well, not really, of course). The objects of the Kuiper belt have another team because of weak beyond the orbit of Neptune, the solar radiation is not able to remove from their surface ice. But whence came with no ice "Trojans" Jupiter? Indeed, in the district of Jupiter was shining, too, are almost nothing, and besides, they are the color of issuing the lack of relationship with the asteroid belt...

"More research is needed, but perhaps we are looking at one of the oldest materials, known in our Solar system," says the scientist. What from this follows? NASA scientists have suggested that if we do not see such objects anywhere else in the Solar system, we are talking about the "natives" - asteroids born simultaneously with Jupiter in its orbit and is composed of the species found in this area approximately 4.5 billion years ago. Of course, this is not the only possible explanation: in the Solar system many "lost" objects like the same theis, and to attribute jupiterians "Trojans" is possible not only to natives. But if this theory is true, Trojans deserve send to them probe, because then their material is one of the most interesting to study in the Solar system.

A study accepted for publication in Astrophysical Journal, and its Preprint available here.

Prepared according to NASA.