Non@Cambridge

MIT's Infinite Corridor Miracle

As viewed from a stationary point on the earth, the path of the sun through the sky is roughly a circle which moves north and south as the seasons go by. In mid-November and in late January every year, the circular path crosses the axis of MIT's Infinite Corridor, which runs a distance of 825 feet (251 meters) from the main entrance on Massachusetts Avenue through Buildings 7, 3, 10, 4 and 8. When this happens, the setting sun can be seen from the far end of the corridor. By analogy with Stonehenge, this phenomenon is sometimes called "MIThenge". (The same cannot be seen at sunrise because the other end of the infinite corridor is blocked by Building 18.)

Pictures

Here are three photographs of this phenomenon, the first from approximately a third of the way down the corridor on the third floor, and the other two from the entire distance on the second floor. Click for full-size versions.

What you'll see

As the sun becomes better and better aligned with the corridor the amount of floor that is illuminated goes up and up. Since the floor is very reflective this means that the reflected sun can be seen far down the corridor as the event approaches. The orange light reflected onto the ceiling is often striking. This phenomenon is visible for a week or two around the actual sunset days.
At some point, some portion of the sun's disc will be visible from the far end of the corridor. Which part of the disc will be seen first depends on whether the sun is crossing above or below the corridor. If the altitude in the table above is high, the sun will cross the upper right edge of the corridor as seen from the lower left. If the altitude is low, the sun will cross from the center left of the corridor and set below the hill.

The disc of the sun is close to the area of sky visible from the end of the corridor. Therefore if your timing is right and you get a good vantage point you will see almost nothing of the sky except for the interior of the sun's disc.

Observing this event depends strongly on atmospheric conditions. I think the best is a very red sunset. This decreases the total light intensity and makes it possible to see the corridor and the sun at the same time. If the sky is brilliantly transparent right down to the horizon then the setting sun will be too bright to look at. When you use a filter to save your eyes (see below) you won't be able to see much of the corridor.

The period of time during which the sun can be seen from the corridor end is quite short -- no more than two minutes, and only as long as that under ideal conditions.

posted by Non@Cambridge @ 12:18 AM