Explorer Attempts Longest Solo Trip in a Solar-Powered Aircraft The Solar Impulse 2 is currently in flight from Nagoya, Japan, to Hawaii.

"All scientific breakthroughs start with a crazy idea and are first said to be impossible."

André Borschberg sent that tweet yesterday -- and it makes sense he would. The Swiss pilot is testing his own crazy idea: attempting to circumnavigate the world in a solar-powered aircraft.

The solar-powered Solar Impulse 2, which took off from Abu Dhabi in the United Arab Emirates in March, is circling the globe, stopping in 12 cities over five months, in an effort to bring awareness to the potential of solar energy. Currently, Borschberg is a bit more than 22 hours into the longest leg of that journey. The 120-hour solo flight will traverse the Pacific Ocean, flying from Nagoya, Japan, to Hawaii.

Already the Solar Impulse team has broken solar-powered aviation records, but if they are able to complete this 120 hour, five-day, five-night leg of the journey, they will again break world records.

Related: Solar-Powered Plane Completes First Leg of Journey Around the Globe

The Solar Impulse team is calling this leg of the journey "the moment of truth," according to the website where you can track the flight in real time, because it is the longest and riskiest part.

Borschberg and fellow Swiss pilot Bertrand Piccard, who have prepared for this solar-powered feat for a dozen years, are taking turns at the wheel of the aircraft. Takeoff for this current trip was postponed twice already on account of bad weather before the aircraft finally took off yesterday.

The one-seater futuristic aircraft has a 72-meter wingspan, roughly equivalent to a Boeing 747 passenger plane, but weighs only 2,300 kilograms, or approximately the weight of a car. Of particular importance to its ability to take multi-day trips, the Solar Impulse can fly at night.

Related: This Startup Wants to Shine a Light on Far Reaches of the Globe

Check out these pics:

The reason why we are flying to Hawaii is because we want to prove #futureisclean is possible: http://t.co/9OWj3SlBMb pic.twitter.com/71gXnhtUBM

— SOLAR IMPULSE (@solarimpulse) June 29, 2015

Some selfies received directly from #Si2's cockpit today! Great spirit! @andreborschberg http://t.co/kZc17xtmNT pic.twitter.com/pFp20MzhN5

— SOLAR IMPULSE (@solarimpulse) June 29, 2015

From Nagoya to Hawaii: an epic #solar flight across the #Pacific! Stay tuned on http://t.co/JIj9tHK6hl pic.twitter.com/oVjkjqPINR

— SOLAR IMPULSE (@solarimpulse) June 29, 2015

After 16h of flight, #Si2 passed the non-return point & is entering the night. #futureisclean http://t.co/JIj9tHK6hl pic.twitter.com/hh1k1nuRBw

— SOLAR IMPULSE (@solarimpulse) June 29, 2015

The exploration starts together with @bertrandpiccard. I'm now 16 hours fully into the flight! pic.twitter.com/hnKOoLwuC4

— André Borschberg (@andreborschberg) June 29, 2015

All scientific breakthroughs start with a crazy idea and are first said to be impossible pic.twitter.com/lR7zl9mhBP

— André Borschberg (@andreborschberg) June 28, 2015

To tackle the #RTW human challenge, #solarimpulse's pilots draw on of self-hypnosis & yoga http://t.co/vXnPD0Qqri pic.twitter.com/nCEcunNV4K

— SOLAR IMPULSE (@solarimpulse) June 28, 2015

This first flight across the Pacific will be an exploration flight, the longest of @solarimpulse's #RTW mission pic.twitter.com/8QFpqMNYqj

— Bertrand PICCARD (@bertrandpiccard) June 29, 2015

Related: Bright Idea: Startup Aims to Advance Solar Energy in Developing Countries