How to find your star in the night sky
· 3 min read · Named in Light
Your certificate lists two numbers that pinpoint the star anywhere on the sky. Here's how to use them to step outside and look at it.
Every star you dedicate with us is a real star from a scientific catalogue, and your certificate gives its exact address on the sky. With that address, a free app and a clear night, you can find it yourself.
The star's address: right ascension and declination
Astronomers locate stars with two coordinates, a little like longitude and latitude on Earth:
- Right ascension (RA) runs east–west around the sky. It's measured in hours, minutes and seconds, from 0h to 24h.
- Declination (Dec) runs north–south, from +90° at the north celestial pole to −90° at the south celestial pole.
Your star's page and certificate show both, for example RA 18h 36m 56s, Dec +38° 47′. That's Vega, one of the brightest stars in the northern sky.
Step 1: check that your star can be seen from where you live
Whether a star ever rises above your horizon depends on your latitude.
- From the northern hemisphere, stars far to the south (very negative declinations) never come up. From London (latitude 51° N), anything south of about −39° stays below the horizon.
- From the southern hemisphere it's the other way round.
If your star never rises where you are, it's still there. It's just over someone else's horizon, and you can visit it on the sky map any time.
Step 2: pick the right time of year
Stars rise about four minutes earlier each night, so over a year the whole sky passes overhead. A star is best placed around midnight in the season when the Sun is on the opposite side of the sky:
| Right ascension | Best around midnight |
|---|---|
| 0h | late September |
| 6h | late December |
| 12h | late March |
| 18h | late June |
For other values, go roughly two weeks later for each extra hour of RA. Your star will also be visible earlier or later in the night for a couple of months either side.
Step 3: let an app point the way
Planetarium apps show the live sky for your location and can search by coordinates. Stellarium is free and open source, for desktop and phones. Type your star's catalogue number (for example HIP 91262) or its coordinates into the search, and the app will show where to look.
Step 4: find somewhere dark
The faintest star you can see depends on the sky:
- In a bright city, only stars brighter than about magnitude 3 show up.
- In the suburbs, about magnitude 4–5.
- Under a truly dark rural sky, about magnitude 6.
Your star page lists its magnitude. Remember that the scale runs backwards: lower numbers are brighter. If your star is fainter than your sky allows, a pair of ordinary binoculars will usually bring it into view.
Looking up together
Finding the star is often the best part of the gift. Pick a clear night, take a blanket and a flask, and give your eyes 15–20 minutes to adjust to the dark before you start looking.