CiTR

https://www.jpl.nasa.gov/news/news.php?release=2017-293&rn=news.xml&rst=6998

Ice-cream and pizza are being delivered to the International Space Station (ISS). YUM. Venus and Jupiter were aligned and were very close to each other in the morning sky on November 13, 2017. Also, astronomers are using pulsars to track G Waves. Gravitational waves are ripples in space-time. They are created from the collision of black holes or neutron stars, amongst other things. They occur from masses accelerating in space. G waves also result from black holes or neutron stars as they do they dance around each other, before they merge. Most galaxies harbour super-massive black holes at their centers. When 2 galaxies merge (that have super-massive black holes) they produce low-frequency G waves. These G waves from the collision of 2 super massive black holes have not yet been detected. Remember, super massive black holes can have the mass of millions or billions of solar masses. To try to find these kind of G waves, astronomers are using pulsars to help. Pulsars are neutron stars that spin. They spin so fast, that they emit many pulses of radio waves each second. Some pulsars can spin hundreds of times each second. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav), is one group using pulsars to search for G waves. A pulsar, or pulsar timing array, emits radio waves in such a predictable pattern, that if a G wave hits the pulsar, then the distortion in space-time of the G waves can be measured from the distortion, or the offset, of the pulse from the pulsar. Observatories like LIGO detect G waves in the seconds just before 2 black holes or 2 neutron stars merge, but it can take millions of years for 2 BHs or 2 NSs to merge. While they are engaged in this cosmic death dance around each other for millions of years before they merge, G waves are emitted. LIGO cannot detect these types of G waves, but astronomers believe that they can detect these types of G waves. When 2 galaxies merge, their black holes (BHs) will usually merge millions of years later. They will emit G waves while they are doing their death dance around each other, and astronomers believe they can detect the G waves that are emitted in this process.