Southern Constellations from Guyana

Southern Constellations from Guyana

Most star guides are written for the north and treat the far southern sky as out of reach. From Guyana, 7° north of the equator, the Southern Cross, Centaurus, Carina and the two Magellanic Clouds all rise. This lesson shows how high each one climbs, when it is up in the dark, and how to find it.

Tonight's Targets · Celestial Coordinates

From Georgetown you can see almost the whole sky over a year. The north celestial pole sits 6.8° above the northern horizon, and the south celestial pole sits 6.8° below the southern one. So every star more than 6.8° from the south pole rises at some time of year: that is everything north of declination -83.2. Only a small cap around the south pole never comes up.

How high a southern star climbs

A star is highest when it crosses the meridian, the line from due north through the zenith to due south. For a star south of the equator, seen from Guyana, that highest altitude is 90° minus your latitude minus how far south the star is.

• From Georgetown (6.8° N), a star at declination -60 climbs to 90 - 6.8 - 60, about 23°.
• From Lethem (3.4° N), the same star climbs about 3° higher, to 26.6°.
• A star at declination -83.2 just touches the horizon from Georgetown, and one further south never rises.

Two fists at arm's length, about 20°, is roughly how high the Southern Cross gets. That is low enough for houses and trees to hide it, so a clear view to the south matters more here than anything else.

How high can the Southern Cross climb from Georgetown (6.8° N)?

• About 7°
• About 23° (the right answer)
• About 60°
• Straight overhead

The middle of the Cross is near declination -60, so its highest altitude is 90 - 6.8 - 60, about 23°: two fists and a bit above the southern horizon.

The constellations to learn first

• Crux, the Southern Cross. Four bright stars in a small kite: Acrux at the foot, Gacrux at the top, Mimosa and Delta Crucis at the arms. Beside it, the Coalsack is a dark patch in the Milky Way, and the Jewel Box is a small, bright cluster in binoculars.
• Centaurus. Alpha and Beta Centauri, the Pointers, sit east of the Cross and point to it. Alpha Centauri, the nearest star system to the Sun, climbs about 22° from Georgetown. Omega Centauri, the biggest globular cluster in the sky, rises to about 36°, high enough to clear most rooftops.
• Carina. Canopus, the second-brightest star of the night, climbs about 30°. Along the Milky Way the Carina Nebula glows as a hazy patch to the eye under a dark sky, with the Southern Pleiades close by.
• The False Cross. A larger, fainter cross across Carina and Vela, often mistaken for the Southern Cross. The real one is smaller, brighter and has the Pointers beside it.
• Tucana, Dorado and Mensa. The Small Magellanic Cloud, with the globular cluster 47 Tucanae beside it, climbs about 10° from Georgetown; the Large Magellanic Cloud, across Dorado and Mensa, about 13°. Both are galaxies, near neighbours of the Milky Way, and both need a dark sky and a very low, clear southern horizon.
• Scorpius. Not a far-southern constellation, but the best one for a beginner: red Antares stands about 57° up when highest, and the tail curls down into the Milky Way's brightest part.

The Southern Cross and the Pointers over the southern horizon: when the cross stands upright, and the line from its long axis down to the hidden pole.

When each one is up

A star reaches its highest point about four minutes earlier each night, so each part of the southern sky has its season. The table gives the night each showpiece is highest at midnight, Guyana time, from Georgetown: the middle of its season. A month or two either side, it is up in the evening or before dawn.

| Showpiece | Highest from Georgetown | Highest at midnight | | --- | --- | --- | | Small Magellanic Cloud | 10° | early October | | Large Magellanic Cloud | 13° | early December | | Canopus | 30° | late December | | Carina Nebula | 23° | early March | | Southern Cross | 23° | late March | | Omega Centauri | 36° | mid April | | Alpha Centauri | 22° | late April | | Antares, in Scorpius | 57° | late May |

The heights and dates come from the site's own sky engine for Georgetown, as Tonight's Targets computes them.

How high the southern sights climb from Georgetown and Lethem, and the month each is highest in the evening.

How high each Magellanic Cloud climbs in full darkness, month by month, from Georgetown or Lethem.

Which of these never rises from Georgetown?

• The Small Magellanic Cloud
• Achernar
• Sigma Octantis, the faint star nearest the south celestial pole (the right answer)
• Canopus

Sigma Octantis is about 1° from the south celestial pole, much more than 6.8° from it, so it stays below Georgetown's horizon all year. The Small Magellanic Cloud only just clears it, about 10° up at best.

Find them tonight

1. Open Tonight's Targets and check the place in the location bar.
2. Tick the gear you own. The Cross, Canopus and Alpha Centauri need nothing but your eyes.
3. If houses or trees hide your southern sky, tap S, SE and SW under Which way is your view blocked?. The list then drops anything lower than 30° that way.
4. Read The southern showpieces at the top: each is up in the dark tonight with its time and height, or the page says when its season returns.

Houses hide the lowest 30° of your southern sky. On a March night in Georgetown, which showpiece can you still catch?

• The Southern Cross
• Omega Centauri (the right answer)
• The Carina Nebula
• The Large Magellanic Cloud

Omega Centauri climbs to about 36°, so it clears a 30° roofline for a while either side of its highest point. The Cross and the Carina Nebula never pass about 23°, and the Large Magellanic Cloud about 13°.

Next

• Tonight's Targets: everything up in the dark tonight, with your gear
• Celestial Coordinates: declination, the meridian and why the Cross points south
• Dark Skies in Guyana: the Magellanic Clouds need a dark site