Double Double
Where is Double Double?
Look southwest, about 70° up at 20:20 in Lyra.
- Rises
- Always up
- Highest
- 18:48
- Sets
- Never
- Best after dark
- 20:20 · 70°
Can I see Double Double tonight?
From London tonight, Double Double is above the horizon after dark. It’s highest soon after dark, around 20:20, in the southwest at 70°.
At magnitude 4.7 it is visible by eye only from a dark site, away from city lights.
This is position and timing only: clouds, haze and light pollution aren’t included.
What does Double Double look like?
Double Double looks white to the eye (color is easier to see in binoculars). Its spectral type is A3V: white main-sequence star (hotter than the Sun).
Eyes
Just beside Vega, people with keen eyes under dark skies can see two faint stars where most see one.
Binoculars
Easily two stars.
Telescope
At about 100× or more and with steady air, each star splits into a close pair. Small telescopes can do it on a good night.
About Double Double
Epsilon Lyrae is known as the Double Double. Sharp eyes or binoculars show two stars close together beside Vega. A telescope then shows that each of those is itself a close pair, making four stars in all.
The system is about 160 light-years away, and the two pairs orbit each other very slowly.
Splitting both pairs is a favorite test of a telescope’s optics and of the steadiness of the air.
The wide pair is separated by about 3.5 arcminutes. Each of those stars splits into two at a separation of a little over two arcseconds.
The two pairs are thousands of times farther apart than Earth is from the Sun, and each pair takes centuries to complete an orbit.
The area around Vega has other good targets: Zeta Lyrae is an easy pair in binoculars or a small telescope, and the Ring Nebula lies between the stars at the far end of Lyra.
Double Double in Lyra
Questions
What magnification do I need to split the Double Double?
Sources: SkyMate; Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences