Free Astronomy Magazine July-August 2023

22 JULY-AUGUST 2023 ASTRO PUBLISHING game of peek-a-boo — has emerged in just a few years between observa- tions stored in the MAST archive of the NASA/ESA Hubble Space Tele- scope. This could be from yet an- other disc nestled inside the system. The two discs are likely evidence of a pair of planets under construction. TW Hydrae is less than 10 million years old and resides about 200 light-years away. In its infancy, some 4.6 billion years ago, our Solar Sys- tem may have resembled the TW Hy- drae system. Because the TW Hydrae system is tilted nearly face-on as seen from Earth, it is an optimum target for getting a bird’s-eye view of a planetary construction yard. The second shadow was discovered in observations obtained on 6 June 2021, as part of a multi-year pro- gramme designed to track the shadows in circumstellar discs. John Debes of AURA/STScI for the Euro- pean Space Agency at the Space Telescope Science Institute in Balti- Concentric gas and dust discs around the star TW Hydrae by NASA − Bethany Downer I n 2017 astronomers reported dis- covering a shadow sweeping across the face of a vast pancake- shaped disc of gas and dust sur- rounding the red dwarf star TW Hydrae. The shadow isn’t from a planet, but from an inner disc slightly inclined relative to the much larger outer disc — causing it to cast a shadow. One explanation is that an unseen planet’s gravity is pulling dust and gas into its inclined orbit. Now, a second shadow — playing a