Comets, asteroids and other Near-Earth Objects (NEOs) are a fascinating sight to behold, if you can manage to spot one in the night sky.
Many will remember the appearance of Comet Hale-Bopp in the 1990s, or much more recently, the beautiful sight of Comet NEOWISE that made headlines around the world and enticed us all to take a look up at the evening sky.
Asteroid Vesta, for example, is one member of the Asteroid Belt that can also be seen, provided you know where and when to look.
But how do you spot comets and asteroids in the night sky? Find out in our guide below which comets and asteroids are visible tonight and over the coming weeks.
September 2021: minor planet 2 Pallas
Minor planet 2 Pallas is, as its prefix number suggests, the second minor planet discovered. It’s one of the ‘big four’ asteroids which includes 1 Ceres (now re-classified as a dwarf planet), 3 Juno and 4 Vesta.
They were discovered in close proximity to one another between 1 January 1801 and 29 March 1807 (for more on Vesta, read our guide to the brilliantly named ‘Celestial Police‘).
Amazingly, 5 Astraea wasn’t discovered until 8 December 1845, breaking a long period where it was thought that 1-4 were the only such objects.
To date, around one million asteroids have been observed and recorded. The four largest asteroids (in size order) are Ceres, Vesta, Pallas and Hygiea.
The third discovery, 3 Juno, is the 10th largest. 2 Pallas is third largest with a mean diameter around 513km.
Pallas’s discovery is attributed to Heinrich Olbers on 28 March 1802, but it was a close call.
Charles Messier recorded it 23 years earlier while tracking a comet, but he thought it was a star and its identity remained hidden.
In 1801, Giuseppe Piazzi discovered 1 Ceres. While initially believing it to be a comet, its motion was unlike any he’d seen before.
After months being lost from sight, Ceres was recovered by Baron von Zach and Olbers later in 1801.
It was while attempting to relocate Ceres a few months later, that Olbers found Pallas which was nearby in the sky.
It spends much of the month in Pisces, skipping into Aquarius at the end. Starting the month at mag. +8.8 and ending at mag. +8.9, Pallas is an easy target for a small scope.
It’s a B-type asteroid, part of the C-type class, but having a spectral bias towards blue.
August 2021: asteroid 89 Julia
It’s a stony or siliceous asteroid (S-type) discovered in 1866 by French astronomer Édouard Stephan and it’s named after Saint Julia of Corsica.
89 Julia will appear shining at mag. +9.0 near the Water Jar asterism. The Water Jar, or ‘Steering Wheel’, is formed of four similar brightness stars in the northern regions of Aquarius.
It sits south of the triangle that forms the upside-down head of Pegasus and to the west of the faint Circlet asterism in Pisces.
The four stars of the Water Jar asterism are:
- Mag. +4.3 Zeta (ζ) Aquarii in the centre
- Mag. +4.4 to +4.7 variable star Pi (π) Aquarii to the north
- Mag. +4.0 Eta (η) Aquarii to the east
- Mag. +3.8 Gamma (γ) Aquarii to the west
The asterism lies 5˚ east of mag. +2.9 Sadalmelik (Alpha (α) Aquarii) and is quite easy to locate.
At the start of August, 89 Julia is located a little over 1.5˚ south-southeast of Gamma Aquarii and from here tracks west-northwest to pass one-third of a degree south of Sadalmelik on the night of 21/22 August.
On 1 August, Julia shines at mag. +9.5, as mentioned above, brightening to mag. +9.0 on 25 August, when it reaches opposition. It then retains this brightness through to the month’s end.
Consequently, 89 Julia may be observed with a small telescope throughout August. To confirm an observation, image or sketch the region in which you think the asteroid is lurking over the course of several nights.
If you’re looking in the correct place, the asteroid’s star-like dot will appear to move.
July 2021: minor planet 12 Victoria
Minor planet 12 Victoria reaches opposition in July 2021. On 1 July it shines at mag. +9.3, slowly brightening over the rest of the month to a peak of mag. +8.8 at opposition on 30 July.
This makes it an ideal object to find and track with a small telescope.
On 1 July 12 Victoria is located in northwest Aquarius, close to the border with Aquila. This region lacks any really bright stars: the best guides are the mag. +4.4 star 3 Aquarii and 70 Aquilae at mag. +4.9.
On 1 July 12 Victoria sits two-thirds of the way along a line from 3 Aquarii towards 70 Aquliae. Its path arcs as it tracks northwest.
At its brightest, near the month’s close, it lies about 2.5˚ east and a fraction south of mag. +3.2 Theta (θ) Aquilae.
The best way to identify 12 Victoria is to sketch or image the field you suspect the asteroid to be located within over the course of several nights.
If 12 Victoria is in this field, its movement will reveal it. In order to achieve this, the field must be recorded with field stars below the threshold of the asteroid, say at least mag. +9.5.
12 Victoria was discovered on 13 September 1850 by John Russell Hind. Although officially named after the Roman goddess of victory, it was also named in honour of Queen Victoria.
It’s a siliceous or stony (S-type) asteroid, around 120km-across, orbiting within the main belt between Mars and Jupiter.
Its apparent magnitude varies between +8.7 and +12.8, making this opposition quite favourable.
12 Victoria’s orbit takes it out as far as 2.85 AU and in as close as 1.82 AU from the Sun.
Studies of its elongated shape suggest that it might be a binary object, the primary chunk having an irregular shaped moon in mutual orbit around it.
June 2021: See Asteroid 30 Urania
Asteroid 30 Urania was discovered by the English astronomer John Russell Hind on 22 July 1854. It reaches opposition on 14 June 2021, when it can be located against the stars of the constellation of Ophiuchus, the Serpent-bearer.
Urania is a main belt asteroid. Its shape and dimensions were measured using a technique known as speckle interferometry, which revealed the asteroid to be elliptical with a longest dimension of 111km and narrowest of 89km.
At its brightest it can be mag. +9.4, so this opposition doesn’t present it at optimal brightness. It takes 3.64 years to orbit the Sun, an orbit that takes it out as far as 2.67 AU and as close as 2.07 AU.
Urania is an S-type or siliceous asteroid, a class that has a stony or mineralogical composition. S-type asteroids account for about 17% of asteroids.
Strictly speaking Urania starts the month in Sagittarius, the Archer, 2˚ north of mag. +4.2, 3 Sagittarii. This positions it very close Sagittarius’s western border and tracking west.
It’s not long before Urania crosses this invisible demarcation line, slipping into Ophiuchus in the early hours of 3 June.
Urania remains above or equal to mag. +11.0 all month, a viable target for a small telescope, but beyond average binocular range.
Its track this month takes it 2˚ south of the mag. +7.4 globular cluster NGC 6401 on the nights of 6/7, 7/8 and 8/9 June.
It passes 0.5º south of mag. +3.3 Theta (θ) Ophiuchi on 22/23 June.
By the month’s end, it’s located 4˚ east-northeast of the mag. +6.8 globular cluster M19. The bright skies found near the June solstice will make locating even a mag. +11.0 object trickier than normal.