Archive for the Uncategorized Category

News of the Views

Posted in Uncategorized on July 28, 2019 by telescoper

Just a quick post to mention that at some point in the early hours of Saturday morning the total number of views of this blog exceeded four million.

I have no idea whether that’s a lot or not for a blog , but I am vastly tickled by the level of interest, which has been fairly steady for about a decade now.

Thanks to everyone for reading (or at least viewing) my ramblings!

P. S. Interestingly, over the last year the six countries with most views were (in decreasing order): UK, USA, Hong Kong SAR China, Germany, Ireland and Australia. I’m quite surprised to see Hong Kong so high but wish all my readers there all the best in what seem to be turbulent times!


The Last Resting Place of the Hubble Parameter?

Posted in Uncategorized with tags , , , on July 22, 2019 by telescoper

Last week was rather busy on the blog, with a run of posts about the Hubble constant (or, more precisely, the  present value of the Hubble parameter) attracting the most traffic. Somehow during all the excitement I allowed myself to be persuaded to write a piece for RTÉ Brainstorm about this issue. My brief is to write a detailed account of the current controversy in language accessible to a lay reader in not more than 800 words. That’s quite a challenge. Better get on with it.

Perhaps after that I’ll be able to lay the Hubble parameter to rest, at least for a while:

The original photograph (and joke) may be found here.

New Publication at the Open Journal of Astrophysics!

Posted in Uncategorized with tags , , , , , , , on July 19, 2019 by telescoper

I was a bit busy yesterday doing a number of things, including publishing a new paper at The Open Journal of Astrophysics, but I didn’t get time to write a post about it until now. Anyway, here is how the new paper looks on the site:

The authors are Tom Kitching, Paniez Paykari and Mark Cropper of the Mullard Space Sciences Laboratory (of University College London) and Henk Hoekstra of Leiden Observatory.

You can find the accepted version on the arXiv here. This version was accepted after modifications requested by the referee and editor. Because this is an overlay journal the authors have to submit the accepted version to the arXiv (which we then check against the copy submitted to us) before publishing. We actually have a bunch of papers that we have accepted but are awaiting the appearance of the final version on the arXiv so we can validate it.

Anyway, this is another one for the `Cosmology and Nongalactic Astrophysics’ folder. We would be happy to get more submissions from other areas of astrophysics. Hint! Hint!

P.S. Just a reminder that we now have an Open Journal of Astrophysics Facebook page where you can follow updates from the Journal should you wish..

Bullying at ETH Zürich leads to a dismissal

Posted in Uncategorized with tags , , , , on July 17, 2019 by telescoper

I was wondering why this old post from 2017 (which was my busiest post of the year back then) has been experiencing a resurgence in traffic over the last few days, and I’ve only just found out the reason.

According to this article, Eidgenössische Technische Hochschule (ETH) Zürich has taken formal action to dismiss a professor from the former Institute for Astronomy. This follows a scandal about bullying in the Institute of Astronomy, which led to the Institute being closed down. The Professor against whom the allegations of bullying have been made is Marcella Carollo, who is not named in the article I linked to above but is named in this more complete account (in German).

This would be the first time in the history of the ETH that a Professor has actually been dismissed.

It has taken quite a while to get this far with this very sorry case – it would have been far better had the complaints about Prof. Carollo been dealt with sooner, but if there is any good to emerge it will be that ETH puts in place better processes for the supervision of early career researchers generally, and particularly for dealing with allegations of bullying.

The Buddleian Library Cat

Posted in Uncategorized with tags , , on July 11, 2019 by telescoper


I’ll get my coat.

Scientific Challenge

Posted in Uncategorized on July 6, 2019 by telescoper

I’m gradually coming to the conclusion that not everything on social media that purports to be from an expert is necessarily scientifically valid. Shocking, I know.

Here’s an example:

I’m afraid I failed this challenge. Can you do better?

And no it shouldn’t be π21.

The Summer Solstice 2019

Posted in Uncategorized with tags , , , , , , on June 21, 2019 by telescoper

The Summer Solstice in the Northern hemisphere happens today, Friday 21st June 2019, at 16.54 Irish Time (15.54 UTC). Among other things, this means that today is the longest day of the year. Days will get shorter from now until the Winter Solstice in December. Saturday June 22nd will be two seconds shorter than today!

This does not mean that sunset will necessarily happen earlier tomorrow than it does today however.  This is because there is a difference between mean solar time (measured by clocks) and apparent solar time (defined by the position of the Sun in the sky), so that a solar day does not always last exactly 24 hours. A description of apparent and mean time was given by Nevil Maskelyne in the Nautical Almanac for 1767:

Apparent Time is that deduced immediately from the Sun, whether from the Observation of his passing the Meridian, or from his observed Rising or Setting. This Time is different from that shewn by Clocks and Watches well regulated at Land, which is called equated or mean Time.

The discrepancy between mean time and apparent time arises because of the Earth’s axial tilt and the fact that it travels around the Sun in an elliptical orbit in which its orbital speed varies with time of year (being faster at perihelion than at aphelion).

Using a rapid calculational tool (Google), I found a table of the local mean times of sunrise and sunset for Dublin around the 2019 summer solstice. This shows that today is indeed the longest day (with a time between sunrise and sunset of 17 hours and 10 seconds), but sunset on 22nd June is actually a bit later than this evening, while sunrise is a bit later.

In fact if you plot the position of the Sun in the sky at a fixed time each day from a fixed location on the Earth you get a thing called an analemma, which is a sort of figure-of-eight curve whose shape depends on the observer’s latitude. Here’s a photographic version taken in Edmonton, with photographs of the Sun’s position taken from the same position at the same time on different days over the course of a year:


The summer solstice is the uppermost point on this curve and the winter solstice is at the bottom. The north–south component of the analemma is the Sun’s declination, and the east–west component is the so-called equation of time which quantifies the difference between mean solar time and apparent solar time. This curve can be used to calculate the earliest and/or latest sunrise and/or sunset.