Astronomers continue refining the precision of distance measurement techniques to better understand the dimensions of the universe. Calculating the age of the universe, its expansion rate, and the nature of dark energy all depend on the precise distance measurements to stars and galaxies. If the astronomical yardsticks are off, the astronomical interpretation may be flawed. The most reliable method for making astronomical distance measurements is to use straightforward geometry where the 186-million-mile diameter of Earth's orbit is used to construct a baseline of a triangle, much as a land surveyor would use. If a target star is close enough, it will appear to zigzag on the sky during the year as a reflection of Earth's orbit about the Sun. This technique is called parallax. The stars are so far away that the angle of this parallax shift is incredibly tiny. An innovative new observing technique has extended Hubble's yardstick 10 times farther into our galaxy, out to a distance of 7,500 light-years from Earth.
Planetary science: A moon of Saturn hides an ocean
Nature 508, 7495 (2014). doi:10.1038/508153a
Beneath Enceladus's south pole lies a watery ocean that could hold organic molecules that form the basis of life.Luciano Iess at the Sapienza University of Rome and his colleagues analysed gravity measurements from the Cassini spacecraft during three flybys of this moon of Saturn
Students following 'Gaia Live in School' event
Will Gaia discover planets that humans would be able to live on? What is a quasar? How many people are actually working on the mission at the moment? These are just some of the varied questions that school students put to some of ESA’s Gaia experts during the Gaia Live in School Event on 25 March 2014.
More than 2000 students, mainly aged 10-12 years old, from 34 schools in 10 European countries followed a live webcast from the Gaia mission planning room at ESOC, ESA’s spacecraft operations centre in Germany. This special webcast gave students a unique opportunity to see behind the scenes of the Gaia mission, with Timo Prusti, the Gaia Project Scientist, and David Milligan, the Gaia Spacecraft Operations Manager answering many of the students’ questions.
Each school participating in the Gaia Live event was linked to a leading research institute in its area. On the day of the event, two postgraduate students, the ‘Gaia Explainers’ from each institute, went into the schools to deliver lively and interactive presentations about Gaia. Hands-on demonstrations and videos introduced the school students to the mission, and to key concepts such as the Solar System, the Milky Way and parallax, to aid their understanding of the science of Gaia before linking up to the live webcast.
Thumbs up at 'Gaia Live in School' event
In the first part of the live webcast students watched David Milligan describe Gaia’s journey to its orbit about L2, a gravitational equilibrium point that is 1.5 kilometres from Earth, how the spacecraft is operated, and how data are sent to and from the satellite. Timo Prusti continued by explaining why it is important to make a 3D map of the Milky Way, how Gaia will help to reveal our Galaxy’s history, and the other exciting discoveries Gaia will make.
Timo and David then answered a range of excellent questions from the schools, which had been submitted in advance of the event. The webcast further stimulated the students’ curiosity, and even more questions for the experts came streaming in from all 34 schools to ESOC by web chat – as many as possible were answered live on air.
Following the webcast, the postgraduate students completed their sessions in the schools with another question and answer session, as well as further demonstrations and activities.
Finnish students participating in 'Gaia Live in Schools' event
In preparation for the event the postgraduate students participated in an intensive training course, held at ESTEC, where they explored how to present science concepts to groups of school students. Working together with the teachers involved at each school, the local event programmes were adapted to ensure that they were relevant for each participating school audience. The enthusiasm of the teachers helped ensure the success of the event at each school.
The event was organised as a partnership between the Gaia Research for European Astronomy Training Network (GREAT) and ESA, with many of the ‘Gaia Explainers’ being students in the GREAT Initial Training Network.
Watch the replay of the ESOC part of the Gaia Live event here.
For more information about the event and the schools taking part, visit the GREAT event web page.
Authors: Rebecca Barnes (HE Space Operations for ESA), Nicholas Walton (Institute of Astronomy, University of Cambridge)