Formation and evolution of the Solar System owe its substantially lower mass simply to having formed a few million years after Jupiter, when there was less gas available to consume. T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, those planets accumulated little hydrogen and helium—not more than each. Uranus and Neptune are sometimes referred to as failed cores. The main problem with formation theories for these planets is the
Solar cycle 24 to trigger a radio blackout. Larger than the planet Jupiter, the AR 12192 sunspot was visible during a partial solar eclipse seen in North America. The sun emitted a mid-level solar flare, an M7.9-class, peaking at 4:16 a.m. EDT on June 25, 2015. In early November 2015, solar flares disrupted the air traffic control system in central and southern Sweden, causing heavy delays for passengers. A sunspot group originally attributed to the new solar cycle 25 is observed. The sunspot numbers continue to decline. During 2016, there were 26 days with no sunspots (preliminary numbers). As of 31 March, preliminary