Astroblog: All Five Bright Classical Planets Lined Up in the Morning Sky (23 January

Friday, January 22, 2016

All Five Bright Classical Planets Lined Up in the Morning Sky (23 January - 22 February 2016)


The sky looking north-east on the morning of January 30th, an hour before sunrise. Click to embiggen.	The sky looking north-east in January 2015, the last time all the bright planets were together in the morning sky. On the 18-22nd of December 2004 they were in the order they are in from the Sun (Mercury, Venus, Mars, Jupiter Saturn) Click to embiggen

As you have probably heard by now, for the first time since January 2005 all five bright classical planets (Mercury, Venus, Mars, Jupiter, Saturn) will be in a line in the morning sky (although some stories confuse alignment, when the planets are close together in the sky, with line-up, where they are all strung out).

This will be rather cool to see, but unfortunately, until around the middle of next week most of southern Australia won't see it.


The sky looking north-east in Adelaide on the morning of January 23rd, an hour before sunrise. Mercury is very close to the horizon and hard to see.	The sky looking north-east in Adelaide on the morning of January 23rd, half an hour before sunrise. Mercury is higher above the horizon but swamped in the twilight.

While Mercury is in the morning skies, it is still very close to the Sun, and still relatively dim. While it is magnitude 1.3, and objects this bright are easy to see when the sky is fully dark, in the twilight glow Mercury will be very hard to spot without binoculars. The best time to spot Mercury is at nautical twilight, and hour before sunrise, the sky is still darkish, and Mercury will stand out.


The sky looking east in Darwin on the morning of January 23rd, an hour before sunrise.	The sky looking east in Brisbane on the morning of January 23rd, an hour before sunrise.	The sky looking east in Sydney on the morning of January 23rd, 45 minutes before sunrise.

The bad news is that for most of Australia south of the latitude of Brisbane, Mercury either doesn't rise before nautical twilight or is very low at nautical twilight, unless you have a clear, level hroizon like the seas or a dessert you won't get to see it.

Take this weekend for example (23-24 January). In Brisbane, an hour before sunrise, Mercury is 5 degrees (just under a hand-span) from the horizon an hour before sunrise, while in Sydney Mercury doesn't really rise until 50 minutes before sunrise.

However, Mercury rapidly rises above the horizon getting substantially brighter (and closer to Venus). By the middle of next week Mercury is becoming easier to see in Southern Australia. By the 30th Mercury is easily visible an hour before sunrise. It is highest above the horizon (around one and a half hand-spans at nautical twilight for most of Southern Australia) on the 7th, and then is reasonably visible to around the 20th-22nd of February.

As an extra treat, Venus and Mercury be 6 degrees (around a hand-span) or closer from February 4th on, and the pair will be closest on February 13th.


The sky looking north-east on the morning of January 30th, an hour before sunrise. Click to embiggen.	The sky looking north-east on the morning of February 6th, an hour before sunrise. Click to embiggen.

To make things even better the Moon marches down the planetary line-up, giving great morning views.

The waning Moon is close to Jupiter on January 28, the bright star Spica on January 31, Mars on February 2. On February 3 the crescent Moon forms a triangle with the bright star Antares and Saturn. On February 4 the crescent Moon is close to Saturn. Then on the 6th the thin crescent Moon, Venus and Mercury form a triangle. On the 7th the very thin crescent Moon is close to Mercury.

So don't be discouraged if you can't see the line-up this weekend, there are plenty of morning line-up sights coming over the next few weeks .

Labels: Jupiter, Mars, Mercury, Moon, Saturn, unaided eye, Venus