Watch for Algol at its minimum

Watch for Algol at its minimum

On clear February evenings, the variable star Algol (Beta Persei), in the constellation Perseus, is high overhead from central UK locations. An eclipsing binary, this star “winks” in brightness every 2.87 days, dipping from its normal magnitude 2.1 to a minimum of around 3.4, as its dimmer orange-yellow secondary passes in front of, or eclipses, the brighter bluer primary. Read more

Love Is All Around – and also in the sky.

Love Is All Around – and also in the sky.

February is usually a cold, dreary month, but as we move towards the middle week, we can feel the warmth of spring and summer just around the corner.  And Valentine’s Day on 14 February gives us the chance to share this warmth and love with our partners and companions in life.

In the sky, there are a couple of romance-themed objects on view this month, the best known of which is the Heart Nebula in Cassiopeia, officially known as IC 1805. This delicate emission nebula glows red by the light of hydrogen, ionised by the light of small cluster of stars at the centre of the nebula. Its blue and orange colours come from emissions from ionised sulphur and oxygen, respectively.

The Heart Nebula in Cassiopeia. Credit: Ross Gould. Sky-Watcher Esprit ED 80, ZWO ASI533MC

This lovely object was discovered by the great deep sky astronomer William Herschel on 3 November 1787 and is almost four times the size of the full Moon. You can find the Heart Nebula high in the north-western sky during February, between Cassiopeia and Cepheus, not far from the famous Double Cluster. However, don’t get your hopes of spying a glowing heart in the sky too high – it’s a very faint object. However, it’s a popular target for astrophotographers equipped for long-exposure photography.

Real lovebirds will have to wait until past midnight in February to locate another heart-shaped object low in the south-west, the Antennae Galaxies. When seen at correct right angle, these two galaxies are lovingly wrapped around each other in an enormous heart-shaped collision of stars, dust and gas.  Located low in the constellation of Corvus the Crow, these galaxies are listed as NGC 4038 and NGC 4039 and also in Sir Patrick Moore’s Caldwell catalogue as objects 60 and 61. The main body of the collision is indeed heart-shaped but the galaxies are more popularly known as the Antennae Galaxies because of the two trails of stars emerging from them which look like insects’ antennae.

The heart-shaped Antennae Galaxies – NGC 4038/9 Credit: Star Shadows Remote Observatory and PROMPT/CTIO (Jack Harvey, Steve Mazlin, Rick Gilbert, and Daniel Verschatse)

These galaxies were also discovered by William Herschel in 1785 and are located around 50 million light years from us. At around 11th magnitude, these are not bright objects, and the faint heart-shaped streams are really only seen on photos. To see them on Valentine’s Night you will need at least a 150 mm telescope and a clear sky to the south-west after midnight – and a very understanding partner.

Comet 144P/Kushida hiding in the Hyades

Comet 144P/Kushida hiding in the Hyades

Periodic comet 144P/Kushida moves through the Hyades open cluster in Taurus during the first week of February, making it easy to spot with binoculars or a small telescope.

Comet 144P/Kushida
Comet 144P/Kushida was caught on the edge of a frame in early January 2024 Credit: Mark Hardaker

On 4 February, the comet will be visible just north of Gamma Tauri, the tip of the V-shaped face of the celestial bull. During the month it will pass through the cluster, its position changing every night.  On 10 February, it will pass only 7 arcminutes from brilliant Aldebaran, fading slowly as it heads away from us and reaching Orion by the end of March.

Although only magnitude 9 or so, the comet should be visible as a pale grey patch in good binoculars, especially as the Moon will be new on 9 Feb. Larger telescopes will show the comet nicely, while astrophotography will show the distinct greenish glow often associated with comets.  This is caused when diatomic carbon (C2) molecules in the “coma” or nebulous envelope surrounding the nucleus, are excited by the Sun’s ultra-violet light.

Chart 1a
Comet 144P/Kushida moves through the Hyades during February, passing very close to Aldebaran on 10 Feb. Credit: Mark Hardaker

Comet 144P/Kushida was discovered in 1964 by Yoshio Kushida and has an orbital period of 7.366 years. At its most distant, its orbit takes it well past Jupiter, while the comet reaches perihelion no nearer than 1.4 AU from the Sun, outside Earth’s orbit.

Look for comet 62P/Tsuchinshan in January skies

Look for comet 62P/Tsuchinshan in January skies

Comet 62P/Tsuchinshan passed perihelion, the closest point to the Sun in its orbit, on 23 December last year, but is still showing nicely in Virgo in the late evening sky.  It’s not a naked eye object and you will need good binoculars or a small telescope to see it.

Comet 62P/Tsuchinshan
Comet 62P/Tsuchinshan in Leo on 9 Jan 2024. Credit: Gideon van Buitenen.

The comet has a typical green ‘coma’ surrounding its nucleus, caused by excitation of diatomic carbon (C2) in its thin atmosphere. A faint tail has been seen but is now subsiding as the comet starts to recede from the Earth and Sun. During the next month or so, the comet will pass into the ‘realm of galaxies’, an area in Virgo peppered with faint nebula.  It will be a challenge to distinguish the comet from these galaxies.

62P/Tsuchinshan
62P/Tsuchinshan moves towards Virgo’s “realm of galaxies” this month. Click to enlarge. Credit: Gideon van Buitenen.

62P is also known at Tsuchinshan 1. The comet was discovered on 1 January 1965 at the Purple Mountain Observatory in Nanjing, China.  It orbits the Sun approximately once every 6.2 years, journeying out beyond Jupiter.  At its nearest to the Sun, its orbit brings it no nearer than a point between the Earth and Mars.

The brightness of a comet is very difficult to predict, as it depends on the scattering of sunlight from dust in the comet’s coma and tail. The amount of dust varies as the comet rotates and as its distance from the Sun changes. This often results in sudden increases in the comet’s brightness, known as outbursts, as gases sublime from the from the nucleus, bringing dust with it. Comet 62P/Tsuchinshan will probably be around magnitude 9, fading to 10 in the next few weeks.