Last updated August 21, 2017 at 10:37 am
Catch up on the latest astronomy and astrophysics news with Starstuff every fortnight.
Weird Signal From Alien Star Not Aliens
Astronomers recently announced they found a weird, never before seen radio signal emanating from near star Ross 128. Sensational headlines appeared based on the theoretical possibility of it having been a transmission from an alien civilisation, although the astronomers stressed it was “at the bottom of many other explanations.”
After studying the signal closely the explanation has been found for the repeated pattern of sliding down a scale of frequencies. According to Professor Abel Mendez who was part of the team which discovered the signals, “The best explanation is that the signals are transmissions from one or more geostationary satellites.”
This came as a surprise as the group had never seen similar signals from satellites before, however geostationary satellites, which are positioned over the Equator, would pass between the observatory being used for the study and Ross 128. Not all the weirdness has been dispelled though, with certain features of the signal still not fully explained, however Mendez is certain there are satisfactory explanations.
The Moon Could Contain More Water Than Expected
Ancient lunar volcanic deposits have revealed that the interior of the moon could contain far more water than we had previously thought.
India’s Chandrayaan-1 satellite was used to measure the amount of reflected sunlight from pyroclastic deposits. In particular, the researchers were looking for the wavelengths where H2O and OH absorb light. Based on the amount of absorption of light they found these deposits contained significant amounts of water.
As pyroclastic deposits are formed from magma forced up from the centre of the planet, the presence of water indicates that the centre of the moon must also contain water. “Our work shows that nearly all of the large pyroclastic deposits also contain water, so this seems to be a common characteristic of magmas that come from the deep lunar interior,” lead researcher Ralph Milliken told Space.com “That is, most of the mantle of the moon may be ‘wet.’”
Water has previously been found around the lunar poles, but that is thought to be a result of hydrogen being delivered by solar winds. The presence of water in the moon’s mantle suggests that water was also delivered to the moon very early in its formation. However, the mechanism for this is still unknown.
This finding may change the approach of future manned missions to colonise the moon, as these pyroclastic deposits could potentially be mined for their water content instead of relying on the water at the lunar poles.
Many More Comets in our Solar System Than We Thought
It turns out the outer reaches of our solar system are far more crowded than we thought. New analysis of data from the WISE probe has suggested that there are as many as seven times more large comets skirting the edges of our solar system than previously estimated.
Using all-sky survey data collected in 2011 by the spacecraft, the researchers discovered the discrepancy in the number of comets measuring larger than 1 kilometre in size. These comets take more than 200 years to orbit the sun, in some cases up to tens of thousands of years, so are notoriously elusive to find.
It’s thought these comets probably emerged from the Oort Cloud, a region of icy fragments left over from the formation of the solar system. This region is found even further out than the Kuiper Belt which surrounds our solar system. Given their distant orbit there is essentially no risk to Earth.
Watching a Star Die
In June a group of astronomers around the world were in the box seat for a unique event – watching a star’s death as it happened.
The explosive destruction of the star released as much energy in 40 seconds as the Sun will in all its lifetime, making it bright enough that a person looking in the right direction with just a pair of binoculars stood a good chance of seeing it happen. The energy released by the star was in the form of a gamma ray burst – a beam of radiation just 2 degrees wide. This tight focus makes it chance that it happened to be aimed at Earth allowing it to be observed.
The gamma ray burst was first detected by a pair of satellites monitoring the sky for just these events, the Fermi Gamma-ray Space Telescope and the Swift Gamma-Ray Burst Mission. Within seconds, they transmitted the coordinates of the burst to a network of land-based robotic telescopes which quickly reacted and repositioned. One of the first to react was the MASTER-IRC telescope in the Canary Islands, which collected optical light while the initial phase of the explosion was still occurring, including rare data on the relative polarisation of the burst.
By observing the burst from this massive star, scientists are hopeful they can answer a number of questions about how they erupt, including questions about how the beams are directed. Analysis of the event is continuing, but initial observations seem to indicate the beams are tightly controlled by extremely powerful magnetic fields within the explosion.
The Old Bombers Which Will Chase The Eclipse
When a total solar eclipse sweeps across the United States on August 21, two converted bomber aircraft will be in prime position. Operated by the Airborne Science Program of NASA, the twin planes will chase totality across the country.
Between them, the two aircraft will collect 8 minutes of observations of the eclipse, far more than the 2 minutes and 40 seconds able to be collected by a ground based telescope. Bristling with cameras and sensors and travelling at an altitude of 50,000 feet (above 90% of the Earth’s atmosphere), the aircraft will be collecting extremely accurate measurements of the solar corona to better understand how energy moves throughout the sun’s atmosphere.
During the darkness of totality the cameras will also be turned towards Mercury to measure the infrared radiation coming from the surface of the solar system’s smallest planet, which would usually be concealed by the infrared radiation from the sun. These measurements are hoped to help explain how the planet’s surface changes from day to night, which could in turn reveal information about its composition and properties.
Ross 128 signal image courtesy of PHL at UPR Arecibo
Moon water mapping image courtesy of Milliken lab/Brown University
Gamma ray burst image courtesy of S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar, E.Ivanov, E.Katkova, N.Orekhova, A.Perkov (OJS RPC PSI, Russia), A.Biryukov (SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal University, Russia)
WB-57F image courtesy of NASA/JSC