| # | Clue | Answer As Given | Value | Round | Category | Air Date | Show |
|---|---|---|---|---|---|---|---|
| In 1679 Danish astronomer Ole Romer was the first to figure out the speed of this | light | $800 | DJ | ASTRONOMY | 2004-09-10 | #4600 | |
| A planet's albedo is the ratio of the amount of this reflected by it to that falling on it | light | $600 | DJ | ASTRONOMY | 1993-02-17 | #1953 | |
| In 1675 Danish astronomer Olaus Roemer announced the 1st real measurement of the speed of this | Light | $600 | DJ | ASTRONOMERS | 1990-04-24 | #1312 |