future

  A dark halo is the inferred halo of invisible material (dark matter ) that permeates and surrounds individual galaxies, as well as groups and  cluster of galaxies . Evidence for the existence of dark matter first came from studies of the motions of stars and gas in galaxies. For example, the quantity and distribution of luminous matter within disk   galaxies cannot account for the rotation curves observed, implying a significant invisible component. In a similar manner, velocity dispersions measured in the outer regions of elliptical    galaxies are higher than expected given the luminous matter within the galaxy. Estimates based on these considerations suggest that perhaps as much as 90% of the matter present in galaxies is in the form of dark matter. Evidence for dark matter is also found through observations of the motions of galaxies in groups and clusters. Using a similar argument to that applied to stella...

  Astronauts on the International Space Station have shared a bird’s eye view of Aotearoa without (mostly) its long white cloud. The station took about three minutes to track from the west side of the lower South Island to the east of the North Island on Monday, passing over the West Coast, Wellington and Hawke’s Bay on its way. Video tweeted by ISS Above – a device that streams live views of the earth – showed the view from the station as it flew over above the country. The snow-capped Southern Alps can be clearly seen, and eventually the lower and eastern edges of the North Island are also in shot. According to MetService, a west to southwest low brought clear skies across the country on Monday, making it possible for the country to be seen so clearly from space. Fresh snow had also recently fallen across much of both islands, which is visible in the video. The ISS Above Twitter account said that the three-minute video shows one of the longest passes the space station can get acr...