Specialised search engines (earth and planetary science data bases).
Although primarily intended for professional scientists, these data bases can also be of value to the highschool teacher and student. Those referenced here are all accessible to you.
If you are interested in really professional information (which will require subscription and payment) then have a look at SERIOUS DATABASES.

500 Natural sciences

520 Astronomy

550 Earth sciences

 
These pages maintained by Dr Georg R Douglas, Hamrahlíð College, 105 Reykjavík, Iceland