On this page: Notes and News / Articles / Letters / Reviews / Meetings / BAA Update / Observers' Forum

From the President / Meteor Section: the season's grand finale / Comet prospects for 2000 / Aurora Section / Venus: the twilight zone, 1999 / A TLP in Langrenus crater / A double Good Lighting Award in Alloa / A colourful Saturn / The two faces of August's eclipse

Two types of aurora are frequently observed from Scotland, the one discrete and the other diffuse. The discrete aurora is a highly active event popularly known as the Merry Dancers. It is a short-lived, rayed arc with a sharp lower border and is usually associated with intense magnetic activity. These features indicate that it is generated by boundary plasma sheet electrons. It is a discrete arc that has migrated south with the discrete auroral oval in response to increased magnetic activity. In contrast, the diffuse aurora is a quiet event popularly known as the Northern Dawn. It is a long-lived, homogeneous arc with a diffuse lower border and is usually associated with weak magnetic activity. These features indicate that it is generated by central plasma sheet electrons. It is an arc of diffuse-continuous aurora that has migrated south with the diffuse oval in response to north/south changes in the interplanetary magnetic field. Thus the Merry Dancers stem from the discrete auroral oval and the Northern Dawn from the diffuse auroral oval. (12 pp; colour images)

Some spectrograms of Wolf-Rayet (WR) stars and planetary nebulae (PNe) are captured with a home-made spectroscope attached to a Schmidt-Cassegrain telescope, and the spectra are briefly analysed. The construction and potential of a low resolution stellar spectroscope is discussed together with techniques to capture images.(8 pp)

John Francis Skjellerup made a significant contribution to amateur astronomy in two continents earlier this century, through his cometary discoveries, variable star observations and active involvement in astronomical societies. (11 pp)

(Copies of any of these articles may be ordered from the BAA office.)

The 33rd BAA Winchester Weekend: Easter 1999

The International Workshop on Cometary Astronomy, Cambridge, 1999 August 14-16

---

Letters

• Frederick Archenhold ... Brian Manning
  
• Roman numerals in chronology ... Peter Macdonald
  
• An early observation of noctilucent cloud? ... Michael Gadsden
  

Read the letters here

---

Reviews

Countdown: A History of Spaceflight by T. A. Heppenheimer. John Wiley & Sons, 1997. ISBN 0-471-14439-8 (hbk), 0-471-29105-6 (pbk). Pp x + 398. £13.99 (pbk). reviewed by Nick James

• Cosmology and Controversy: the historical development of two theories of the Universe by Helge Kragh. Princeton University Press, 1999. ISBN 0-691-00546-X. Pp xii + 500, 11.95 (pbk).
  reviewed by Jon Reynolds

• Introduction to stellar winds by Henny J.G.L.M. Lamers & Joseph P. Cassinelli. Cambridge University Press, 1999. ISBN 0-521-59398-0 (hbk.), 0-521-59565-7 (pbk.) Pp xiv + 438, £50.00/£18.95.
  reviewed by Ian Howarth

An introduction to modern cosmology by Andrew Liddle. John Wiley & Sons, 1999. ISBN 0-471-98757-3 (hbk), 0-471-98758-1 (pbk). Pp xiii + 129, £14.99 (pbk). reviewed by Arunas Kucinskas

• Exploring the Moon - The Apollo Expeditions by David M. Harland. Springer/Praxis, 1999. ISBN 0-85233-099-6. Pp xxv + 411, £19.00 (hbk).
  reviewed by Peter Cattermole

---

Meeting reports

• Ordinary Meeting, 1999 May 26
  

---

Observers' Forum

A 1998 Leonid fireball

CCD images of Jupiter and Saturn

...

Jupiter and Saturn imaged by Martin Mobberley in August this year with his 0.36m f/25 Cassegrain and Starlight Xpress SXL8 CCD. Left: Jupiter on August 28 at 00.57 UT, exposure 0.2 sec. The satellite with shadow visible on the disk is Io. Right: Saturn on August 2 at 02.00 UT, exposure 0.8 sec. M. P. Mobberley

---

A copy of this or any other recent issue of the Journal may be ordered from the BAA office.

Back to top of page

Go to the BAA Journal home page