Nicola,
in this course when we are referring to inquiry based learning we are specifically referencing the Curious Minds ESERO Framework for Inquiry that was developed in Ireland. Research can be an inquiry process, but the children should use their scientific understanding to make a testable starter question and then verify it with their research.
So, for solar system facts, a group might share that they know the order of the planets from the Sun and might suggest that the planet closest to the Sun will be the hottest, because…. (their own understanding). They could then research that to see if they are right. They will find that the hottest planet is actually the second planet from the Sun, because of a different reason (its atmosphere) and so they will have to modify their thinking in light of their investigation.
This could then lead to a next step where they model Venus’ atmosphere in some way, possibly by making a model greenhouse from a box and cling film and comparing the temperature inside the box vs outside the box, see this from ESERO: https://esero.ie/wp-content/uploads/2015/01/47_The-ice-is-melting.pdf
Or see this activity for slightly older children from ESERO: https://esero.ie/wp-content/uploads/2015/01/67_The-Greenhouse-effect.pdf