. >> reporter: but this is what xavier mendoza saw from mount hamilton on friday night, a stunning rare display of the northern lights. >> it just made my passion for astronomy a little bit more solidified. >> reporter: hen do sa is a grad student at san jose state. he shared his enthuse yam with professor aaron. >> this is the most impactful event in 20 year, a fantastic hands-on learning experience for the students. >> reporter: beautiful auroras seen in these photos taken in marin and seen across muff of the world stem from a geomagnetic storm reaching earth. >> it's a beautiful experience. nothing too dangerous because we have our magnetic field protecting us around the earth. >> reporter: distinguished professor of astronomy alex took these photos from orinda. >> the red auroras are actually more rare than the green auroras. that was quite special for me to see such an intense red aurora. >> reporter: along with the beauty comes potential for problems for us on earth with telecommunications and power systems. >> when these particles come in, they twang our magnetic field. it's as t