• 13th December - Friends Observing

    Geminid Meteor Shower - Observatory @ 10pm

    The Observatory will be open from 10pm for Friends to observe the Geminid Meteor Shower, whatever the weather!
    If clear we will observe in visual wavelengths, if cloudy we will observe in radio...

  • 16th December - Friends Observing

    The Winter Wreath - Observatory @8pm

    Friends, come to the observatory for an evening of Astronomy!
    If clear we will explore the Winter Wreath, if cloudy there will be an opportunity for astronomical Q&A.


Marlborough College

Welcome to the Marlborough College Blackett Observatory, home to the largest refracting telescope in Wiltshire. The Observatory is a key facility for the study of Astronomy by pupils at Marlborough College. It is open to the public through the Friends of the Marlborough Telescope membership scheme. School and Society visits are welcome, please contact the Director to arrange your visit.

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What's Up!

Week of 5th December 2022

  • Astronomical twilight ends at 18:02 GMT at the beginning of the week and at 18:02 GMT by the end of the week.
  • There are two lunar occultations this week, the first is on Monday afternoon when Uranus (mag +5.7) will disappear behind the Moon at 16:46 UT and reappear at 17:18 UT. The second is on Thursday morning at 04:57 UT when Mars (-1.9) will be occulted by the Moon, reappearing at 05:59 UT.
  • Mars (-1.9) reaches opposition on Thursday, the point in its orbit when it will appear directly opposite the Sun from Earth. This is the best time to observe the planet as it appears at its brightest and largest in our sky. Its close proximity to Earth also makes this the ideal time to travel to Mars! It won’t be at opposition again until January 2027.
  • The Moon is Full on Thursday – the Cold Moon.
  • The Sun currently has five active regions: AR 3153, 3154, 3155, 3156 & 3157. The sunspot number is 68.
  • There are visible evening ISS passes this week as follows:
    Monday 5th: 16:50 (-2.7) W to SE, max 47° & 18:28 (-0.7) WSW to SSW, max 13°
    Tuesday 6th: 17:39 (-0.9) W to S, max 18°
    Wednesday 7th: 16:50 (-1.4) W to SSE, max 26°
    Friday 9th: 16:51 (-0.4) WSW to SSW, max 13°



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Latest News

What's been going on at the Blackett Observatory

1st December

Shell Visit: For the first time this term, the Shell visit was blighted by poor weather with thick fog. Six boys from Cotton House joined GKWJ at the Dome, accompanied by an ex-GCSE Astronomer now in the U6. They were shown around the facility and looked at a selection of astronomical images.

29th November

Blackett Science Lecture: The 18th Blackett Science Lecture was delivered by Dr. Rebecca Smethurst, RAS Research Fellow at Oxford University, to a large audience in the Ellis Theatre. Her lecture was entitled ‘It’s not easy growing a supermassive black hole’. Dr. Becky explained the basics of black hole science (they are sofas, not hoovers!) and then spoke about her research into how black holes increase in size. There is a large disconnect between merger and non merger growth, which is her area of continuing observational based research. Many excellent questions were asked at the end of the lecture, demonstrating how well Dr. Becky had engaged with the audience.

28th November

Outreach Visit: Five members of Marlborough Town Council and the North Wessex Downs AONB came to the Dome with GKWJ and JAG to celebrate the past success of the Marlborough Dark Skies Festival and to look forwards to future collaborations. Patchy cloud allowed opportunistic observation through large gaps. The session started outside to see the waxing crescent Moon, the line up of planets, the Pleiades and a suggestion of the Andromeda Galaxy. The group moved to the 10-inch to view the Moon in great detail, followed by Saturn with its moon, Titan, and then Jupiter with its 4 Galilean moons. Attention turned to the double star Almach and a fuzzy view of the Andromeda Galaxy’s core. The final target was Mars, with a polar ice cap and surface details just visible through variable cloud.

25th November

Outreach Event: GKWJ and JAG were invited to the North Wessex Downs AONB Annual Forum to run a stargazing event in the early evening at the Marlborough Golf Club to highlight the importance of dark skies across the region. A clearing and mostly dark sky provided perfect conditions for over 50 Forum delegates to enjoy a sky tour and views of the Pleiades (M45) through binoculars and Jupiter, Saturn and Mars through an ETX.

24th November

Shell Visit: In an unprecedented run of good fortune for the Shell Visits, predominantly clear skies welcomed the 12 boys from C3 with their tutor, DGR, up to the Dome. GKWJ started the visit outside by pointing out Saturn, Jupiter, Mars and the Pleiades. The group moved inside to the 10-inch to observe Saturn, with Titan visible, and Jupiter with all four Galilean moons visible. The group returned outside to enjoy a closer look at the Pleiades through binoculars and rising Betelgeuse through an ETX. The session ended with a quick look at the Campo meteorite.

Staff Visit: A member of staff with their two young children visited the Dome where GKWJ showed them Saturn and Jupiter through the 10-inch. All 4 of Jupiter’s Galilean moons were visible and at least one moon of Saturn was seen.




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All Sky Eye

The Latest View from the MCBO

The All Sky Camera operates from 30 minutes after sunset through the night until 30 minutes before sunrise. The latest image is updated automatically every 5 minutes and the time lapse video is refreshed each morning at around sunrise. Click the still image to view a large version


Latest Still Image

Most recent time lapse video