US 2021 Coronal Hole : Sun Science 55c. Scott. 5607


US 2021 Coronal Hole : Sun Science 55c. Scott. 5607


Series: Sun Science (2021)

Stamp details: Coronal Hole

Issued date: 18-06-2021 (dd/mm/yyyy)
Face value: 55c.
(FOREVER º - No Face Value)

Format: Pane of 20

Emission: Commemorative
First Day City: Greenbelt, Maryland

Catalogue No:-
Scott (USA): 5607
Michel (Germany): 5840BA
Yvert et Tellier (France): 5449

Designers: Antonio Alcalá

Dimensions (height x width):
31.25mm x 31.25mm

Printer: Banknote Corporation of America
Print Method: Flexographic, Foil Stamping

Perforation: Serpentine Die Cut 10¾ x 10½

Stamp Colors: Multicolored
Gum type: Self-Adhesive

Themes: Sun, Astronomy

Total print: 3,000,000 (estimate)

Note: Stamp from se-tenant block of ten.

Face value US$0.55 on day of issue.

Description:- A coronal hole is a temporary region of relatively cool, less dense plasma in the solar corona where the Sun's magnetic field extends into interplanetary space as an open field.[1] Compared to the corona's usual closed magnetic field that arches between regions of opposite magnetic polarity, the open magnetic field of a coronal hole allows solar wind to escape into space at a much quicker rate. This results in decreased temperature and density of the plasma at the site of a coronal hole, as well as an increased speed in the average solar wind measured in interplanetary space. If streams of high-speed solar wind from coronal holes encounter the Earth, they can cause major displays of aurorae. Near solar minimum, when activity such as coronal mass ejections is less frequent, such streams are the main cause of geomagnetic storms and associated aurorae.
Source: en.wikipedia.org/wiki/Coronal_hole