div class=ts-pagebutton class=gotoPage data-page=1Page 1button div class=ts-imagea href=https:reader042vdocumentsmxreader042viewer20220204055750680a1a28ab0f07ae5028html5page1jpg target=_blank img data-url=auroral-activity-during-aprildecember-1956htmlpage=1 data-page=1 class=ts-thumb lazyload alt=Page 1: Auroral Activity during April–December 1956 loading=lazy src=data:imagegifbase64iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAQAAADYv8WvAAAAD0lEQVR42mP8X8AwAgiABKBAv+vAXklAAAAAElFTkSuQmCC data-src=https:reader042vdocumentsmxreader042viewer20220204055750680a1a28ab0f07ae5028html5thumbnails1jpg width=140 height=200 adivp© Nature Publishing Group1957pdiv