Cetus, the Sea Monster, is a large ancient constellation of the autumn sky, home to the variable star Mira and to Tau Ceti, a nearby Sun-like star.
At a glance
| stars in the figure | 13 |
|---|---|
| nearest star of the figure | Tau Ceti, 11.9 light-years (3.65 pc) |
| farthest star of the figure | Delta Ceti, 650 light-years (199 pc) |
| depth | the farthest is 55 × farther than the nearest |
Read off the piece’s own catalogue, the same values it draws with.
About Cetus
Cetus is one of the constellations catalogued by Ptolemy. It is the monster sent to devour Andromeda, chained to a rock until Perseus rescued her, and it shares the sky with every character of that story. It is one of the largest constellations, lying along the celestial equator below Pisces and Aries, so it can be seen from both hemispheres in the evening in northern autumn.
Its most famous star is Mira, the wonderful, the first star recognised to rise and fall in brightness in a repeating cycle, an old red giant that swells and shrinks so much that it disappears from naked-eye view for months and then returns. Diphda, the brightest star of Cetus, and Menkar, in the monster’s jaw, are orange and red giants.
Cetus also holds some of the Sun’s nearest neighbours. Tau Ceti is a star much like the Sun, a frequent target in the search for planets, and the faint red dwarfs YZ Ceti and the pair BL Ceti and UV Ceti, also called Luyten 726-8 A and B, lie within its borders.
What you see in the piece
Cetus spans an unusually great range of depth: Tau Ceti sits close to the Sun while Delta Ceti lies far out, so flown out to, the monster scatters into stars that have nothing to do with one another.
Questions
Why is Mira called the wonderful star?
Mira is a pulsating red giant whose brightness changes enormously over its cycle, so it appears and disappears from the naked-eye sky. Its regular return gave it its name.
How far away is Tau Ceti?
Tau Ceti, the nearest star of the figure, is 11.9 light-years (3.65 pc) away; the farthest, Delta Ceti, is 55 × farther.