Papers – Page 15 – British Astronomical Association

Noctilucent cloud over Britain & Western Europe, 2017

A summary by the Assistant Director of the Aurora & NLC Section of noctilucent cloud (NLC) activity during the 2017 season.

Jupiter’s North Equatorial Belt & Jet: II. Acceleration of the jet & the NEB fade in 2011–’12

Paper I described the normal features of the North Equatorial Belt (NEB) in recent years. This paper describes an exceptional set of apparently coordinated changes which occurred in 2011–’12, after more localised precursors in 2008 & 2010. The large dark formations on the NEB southern edge (NEBs) progressively disappeared until none remained. In the sectors of NEBs thus vacated, smaller dark features all moved with unprecedented ‘super-fast’ speeds, which were modulated by the few normal features while they lasted before accelerating further. These changes have several profound implications for understanding the dynamics of the region.

The myth of Henry Hudson’s sunspots

This paper examines claims that the explorer Henry Hudson saw sunspots with the naked eye during sea voyages in both 1590 & 1609. It is argued that there is no evidence to link Hudson with the 1590 observations, and that the presumed sunspot of 1609 – accepted by some leading experts in the history of solar activity – is based on a false premise.

The eastern & western elongations of Venus, 2007–’17. Part I. The sunlit hemisphere

Fourteen successive morning and evening elongations of Venus from 2007–’17 are reviewed. The work of 153 observers covered the time period of ESA’s Venus Express and Japan’s Akatsuki missions, and wavelengths from 335–1750nm. Part II will discuss phenomena of the nocturnal hemisphere: the infrared thermal emission from the planet’s surface, and the Ashen Light.

A lunar cryptomare dome near Cavalerius A and Hevelius A

In this study we examine a lunar dome, identified using CCD terrestrial imagery, LROC WAC images, Clementine multispectral data and the LROC WAC-based GLD100 DTM. The dome lies near Cavalerius A and Hevelius A, in a complex region known as Hevelius Formation, showing evidence of ancient (pre-Orientale) mare volcanism and cryptomare deposits.

Alice Grace Cook: An East Anglian meteor observer

Alice Grace Cook (1877–1958, and usually known by her middle name) was one of the first female Fellows of the Royal Astronomical Society. She was also briefly the Director of the British Astronomical Association Meteor Section. However, she is a little-known figure. This paper presents an overview of her life and contributions to astronomy.

The mean distance from the Earth to the Moon

The mean value (over time) of the distance between the centres of the Earth and the Moon is 385,000 km, not 384,400 km as given in many texts. This is based on the Moon’s mean equatorial horizontal parallax.

Jupiter’s North Equatorial Belt & Jet I. Cyclic expansions & planetary waves

This article presents a synopsis of the activity in Jupiter’s North Equatorial Belt (NEB) from 1986–2010, and of the speeds of dark formations on its south edge and bright streaks (‘rifts’) in its interior. In particular I discuss NEB expansion events (NEEs), which took place every 3–5 years during this time, and how the various features of the NEB are involved in them.

The brighter comets of 2013

This report describes and analyses the observations of the brighter or more interesting comets discovered or at perihelion during 2013, concentrating on those with visual observations. Magnitude parameters are given for all comets with observations. Any evolution in the magnitude parameters of those periodic comets with multiple returns is discussed. Additional information on the comets discussed here and on other comets seen or at perihelion during the year may be found on the Comet Section’s visual observations web pages.

The visibility of the Southern Cross from Britain

This paper considers past and future appearances of the southern constellation of Crux in the skies of Britain.