The galaxy is wide, cold and seemingly empty for a civilization that has just recently discovered the secret of inter-stellar travel. When you create an account, the only planets you can see in the Universe-page is your own and, if you have joined an alliance, the planets of your alliance mates. All other coordinates are shown as 'Uncharted' and marked by those coordinates there might or might not be a planet that is inhabited by another civilization.
In order to retrieve information about an uncharted planet, such as its location and score, you have to either scout or scan the planet. Retrieving this information is crucial in case you want to attack the said planet, mostly because you cannot attack a planet if it is uncharted.
In practice, scouting is done by sending a fleet (one ship is enough) to defend an uncharted planet. Travel time to an uncharted planet is naturally unknown to you and thus the remaining travel time won't show up on your Control Panel either. Once your fleet arrives to the planet it will be charted and will show up in your Universe-page.
A big advantage of scouting is that the score of the planet that has been scouted will be updated until you do a scan on that planet. If you plan on attacking a scouted planet then you require to do a Planet Scan on it. Normally this will mean you lose the updating of the planets score, but if you follow through on your attack the score update will resume afterwards. Before you scout someone you should realize that your own coordinates will be visible to the planet you scout, so you will be exposing your own whereabouts as well.
Once you chart a planet, ie. scout or scan it, its basic information (ruler name, planet name, score) will be stored in your scan history. The data in your scan history is what is shown in your Universe-page. This data doesn't update until you either have your fleet arrive to the planet or scan it again. Additionally, if you have the Combat Information Centre built and you are in an alliance, you will also have scan histories of your alliance mates at your disposal. In other words: every time an alliance mate of yours charts a planet, the planet in question will appear as charted for you as well for as long as you stay in the alliance. In case both you and an alliance mate of yours have scouted or scanned the same planet, the newer data will be used.
There is also one more way of charting planets that is exclusive to Lilnosas and Slithins only. Whenever an incoming fleet is detected moving towards a Lilnosa or Slithin planet (ie. the ETA of the fleet changes) the home planet of the incoming fleet will become charted for the Lilnosa/Slithin planet in question and added to its scan history.