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Are they being tugged by Planet Nine?


A six-year search of space beyond the orbit of Neptune has netted 461 newly discovered objects.

These objects include four that are more than 230 astronomical units (AU) from the sun. (An astronomical unit is the distance from the Earth to the sun, about 93 million miles or 149.6 million kilometers). These extraordinarily distant objects might shed light on Planet Nine, a theoretical, never-observed body that might be hiding in deep space, its gravity affecting the orbits of some of the rocky objects at the solar system’s edge.

The results provide a blueprint for finding such systems in the universe’s quieter, emptier regions.

By definition, dwarf galaxies are small and dim, with just a fraction of the stars found in the Milky Way and other galaxies. There are, however, giants among the dwarfs: Ultra-diffuse galaxies, or UDGs, are dwarf systems that contain relatively few stars but are scattered over vast regions. Because they are so diffuse, these systems are difficult to detect, though most have been found tucked within clusters of larger, brighter galaxies.

Now astronomers from MIT.