This special “ eclipse-aware ” shadow map shows how the shadows would fall on Northern Spain at the time of third contact (C3, 8:29 PM local time) in Burgos. A shade map allows you to assess whether the Sun will be visible at a given time across a wide swathe of positions all at once: if the point is in shadow, you can’t see the Sun.

You’ll see that areas in the Hills to north and east of Burgos are in shadow around the time of third contact, meaning the eclipse won’t be visible. Be sure to pan around, zoom in, and check the actual contact times for the locations you’re interested in – generally, you want to be sure everything remains visible for a few minutes AFTER C3 in order to be sure you won’t be watching the Sun set behind a mountain during the eclipse.

There are a few subtleties to be aware of in the shadow map above.

The Sun is not a point light source. Rather, it appears as a disk in the sky, and therefore at times it may only be partially obscured (e.g. during a partial eclipse, or when setting behind a ridge). If the Sun is partially obscured, you’re standing in the penumbra (yellow when Penumbra or Coronal mode selected). Some shade maps don’t make this distinction, treating the Sun as a point light source. This can trick you into thinking you can see the entire Sun, when in fact it would actually be partially blocked.

During a total eclipse, you’re primarily looking at the limb (the edge) of the Moon and the area around it, to view the corona, prominences, the chromosphere, and Baily’s beads. The corona extends very far from the Sun. A naked eye observer can view it easily as far as three times the Sun’s radius. Photographers can capture it at 5× the semidiameter (angular radius) without too much difficulty. With specialist equipment and post-processing, corona at 10× the semidiameter can be visualized.

The pink hues in the map above are the notional “ coronal shadow ”. If you’re standing in the coronal shadow at C3, that means the Sun’s corona is already partly obscured. Beware!