Free Astronomy Magazine March-April 2025

22 MARCH-APRIL 2025 ASTRO PUBLISHING There, grains of dust collided and fused into increasingly large struc- tures. Once they reached a kilome- ter-size, their own gravity started to attract more objects, fueling their growth even further. In a very sum- marized version, this is how we think planets formed. We have seen this process taking place in other planetary systems. However, we also know that not all dust ends up forming planets. Astronomers think that the influ- ence of large planets like Neptune T he Edgeworth-Kuiper Belt (or simply the Kuiper Belt) is a huge structure extending 30 to 50 times the distance from the Earth to the Sun. It is full of icy and rocky objects. But where does it come from? In its infancy, the Sun was sur- rounded by a giant rotating cloud of gas and dust. Much like making a pizza from a ball of dough, by ro- tating over time, the cloud eventu- ally became a flat disc, which we call a protoplanetary disc. by ALMA Observatory Nicolás Lira & Bárbara Ferreira Exocomet belts are changing our understanding of planetary systems