* This text was written by a columnist Tekmundo; Finally learn more.
Earlier this week, the GAIA survey published the latest survey of our night sky, the most complete census ever published, including stars, quasars, galaxies and other celestial objects.
GAIA is a space telescope that was launched in 2013. The instrument monitors the entire sky and creates a survey with the main objective of creating our best three-dimensional map GalaxyA Galaxy. With this map, the mission will provide the position of billions of stars with unprecedented accuracy.
In addition, we will have velocity information in 3 dimensions, which will allow for in-depth study of objects and galaxies. By observing the sky, GAIA is able to capture changes in the brightness of some objects, which can lead to the discovery of exoplanets.
Finally, the telescope will observe more than 500,000 distant quasars, providing fundamentally new data for the ongoing development of Albert Einstein’s general relativity theory.
GAIA MissionSource: ESA-GAIA
What is the ruler of the universe?
It is not easy to measure the distance of an object in the sky. Bright stars can be large or near, while dim stars can be small or even distant. So how do you measure the distance of stars without rulers or without going there?
The branch of distance and space measurement is called astrometry and one of the most accurate techniques is called parallax. The principle of parallax is simple geometry and not difficult to understand. Extend your hand, point your finger in front of you and close one eye at a time. Now, when you change which eye is closed, you can see the clear movement of your finger. You can measure the distance to your finger by knowing the distance between your eyes and nose and the shape of your hand with simple geometry. This is the idea of parallax. But instead of your nose, you have the sun and each eye has the position of the earth at one time of the year.
Illustrated parallax conceptSource: ESA-GAIA
When observing an object, we can map its position in relation to the object in the background. After 6 months we will be on the other side of the sun (i.e. how to change which eye is open) and we can go back to observe the same object. You will notice a small change in the position of this object. With this change we are able to measure your distance!
But not everything is perfect. This technique works very well for near objects, requires more precision for more distant objects and that is where the GAIA telescope comes in, which has unprecedented accuracy! The speed of nearby stars is one arcsecond. The mission will be able to accurately measure the apparent speed up to 0.000001 arcseconds! For scale purposes, 1 arcsecond corresponds to 1/3600 of a degree and the size of a full moon appears in a two degree sky.
This is not an image of a galaxy. Millions of images are together. There is a detailed observation of each point through the GAIA telescopeSource: ESA-GAIA
Camilla de Sa FritasColumnist for Tekmundo, Degree in astronomy and postgraduate degree. She is currently a PhD student at the European Southern Observatory (Germany). The self-styled Galaxy Coroner examines evolutionary conditions for galaxies and possible changes in star formation. He is present on social media as astronomacamila.