Booktradelabels; an interesting collection

I want to share an article from another collector with anyone who is interested:

BOEKHANDELSZEGELTJES ZUID-KENNEMERLAND (Haarlem e.o.); van boekverkopersreclame tot verzamelobject Verzamelingen Boekbinders- en boekhandelsmerkjes worden weinig verzameld in vergelijking met bijvoorbeeld bladwijzers en ex librissen. De grootste openbare collectie bevindt zich in de bibliotheek van de Vereeniging ter Bevordering van de Belangen des Boekhandels van de Koninklijke Vereniging van het Boekenvak [Bijzondere collectie universiteit Amsterdam; ook in […]

via BOEKHANDELSZEGELTJES i.z. uit Zuid-Kennemerland – boekbinderijen en leesbibliotheken — Librariana

unknownskywalker:

Mercury surprises: tiny planet has strange innards and active past

Using observations from NASA’s Messenger spacecraft in orbit around Mercury, researchers observed that the floors of many craters have been tilted substantially. Part of the floor of the Caloris basin has even been raised above its rim. This suggest that internal forces pushed the craters up after the impacts created them, providing strong evidence that Mercury remained geologically active long after its formation.

Researchers also estimated Mercury’s gravity field by precisely radio-tracking Messenger’s movements around the planet. From these estimates, they determined that Mercury has “mascons” (short for “mass concentrations”), which are large positive gravity anomalies associated with big impact basins.

The team’s gravity calculations also suggest that Mercury has an iron core that comprises roughly 85% of the planet’s radius. (For comparison, Earth’s iron core covers about half of its radius.) Further, it looks like a layer of solid iron sulfide overlies Mercury’s core — a feature not known to exist on any other terrestrial planet.

The new findings shed light on Mercury’s past, and on the formation and evolution of rocky planets in general. But they also serve to remind scientists that they’re in for many more surprises as they continue to probe the solar system’s many mysteries.

Above: Perspective view of ancient volcanic plains in the northern high latitudes of Mercury revealed by NASA’s Messenger spacecraft.

demonagerie:

Rylands Medieval Collection, Latin MS 53, f. 58v. Christianus Prolianus and Joachinus de Gigantibus (?), Astronomia (1478)

“Comparative view of the magnitudes of the Sun (a large disc of burnished gold), the Moon (silver), Mars (gold), Venus (gold), Mercury (gold) and Earth (pale). Framed in a green wreath of leaves and blue background.”

astronomy & astrology