If you're in space you can scan the planets in your current system by selecting one in your overview and clicking View in Planet Mode in the selected object control, or right-clicking and selecting View In Planet mode.

All systems within your Remote Sensing skill range (including the current system) can be scanned by opening your galaxy map and selecting the new Planet scan range filter under My Information. Systems within range will be colored, ranging from a large green circle for close systems to a small red dot for distant ones. Select a system, right-click and select Show Info, then select the Orbital Bodies tab. Right-clicking a planet and selecting View In Planet Mode will close the map and start viewing the planet in planet mode.

Selecting a planet to remotely scan

The controls for planet mode are below the current location information in the top left of your screen, possibly hidden underneath other windows. Clicking the Scan button will show you the five resources the planet produces. Alongside each of these is a bar that shows the proportion of the maximum possible a planet can produce is available on this planet. Resource poor planets will only be slightly filled with white, while resource rich planets will be mostly filled. Clicking on one of the resources will scan the planet for that resource, and show it's concentration on the planet, color coded for high/low concentration. Just below the build and scan buttons is a rainbow colored slider. You can grab the triangle handle on the left to show/hide areas of low concentration, and also the handle on the right to emphasise the best areas.

:Note: You can view any planet in planet mode, including the minerals available, regardless of range; you need to be in scan range to view the areas of high/low concentration. This makes the Remote Sensing skill somewhat less important, except as a prerequisite for Planetology and the increased scan accuracy that brings.

Adjusting the sliders to show the hotspots.

Training the Planetology and Advanced Planetology skills will improve the accuracy of your scans, showing more resources, better defined locations, and possibly resource locations that wouldn't be seen without these skills.