APOD 4.5

25 ultraviolet images later, this photo of our vary own sun was produced courtesy of the Solar Dynamics Observatory. In this particular wavelength of the extreme ultraviolet--known as 171 angstroms--the highly ionized iron in the sun's corona can be pinpointed, capturing the distinct characteristic of 600 000 Kelvin temperatures. While the sunspots are not as easily seen in this image as they are in most visible light spectrum photographs, the nature of the sun's unequal magnetic field can be well noted, especially in the band around the solar equator.

APOD 4.4

Within Orion dwells the stellar masterpiece of the Horsehead Nebula, also known on Messier list as M42 and on as Barnard 33 in other catalogues. In honour of the Hubble's 23rd anniversary up in space, this photograph as taken in the infrared spectrum to showcase the magnificent emission nebula typically outshined by Sigma Orionis. We have a good few million years to marvel over this spectacle about 1 500 light-years away, for after that the high energy starlight will destroy this formation; or, more optimistically, sculpt it into something new!

APOD 4.3

What really matters is what's in the soul; and in that of the Queen Aethopia there are many stars forming. While Cassiopeia is, in mythology, scorned for her vanity, her stellar counterpart houses many open clusters in IC 1848, featuring a handful of open clusters, the radio force of W5, and bubbles formed from the winds of forming stars. This soul spans about 1000 light-years, sitting about 6500 light-years away next to its photogenic companion, the Heart Nebula.

Jan H. Oort Sources

"The Bruce Medalists: Jan H. Oort." The Bruce Medalists: Jan H. Oort. 05 May 2012. Web. 22 May 2012. <http://www.phys-astro.sonoma.edu/brucemedalists/oort/>.

"ESA - Space Science - Jan Hendrik Oort: Comet Pioneer." ESA - Space Science - Jan Hendrik Oort: Comet Pioneer. European Space Agency, 27 Feb. 2004. Web. 22 May 2012. <http://www.esa.int/esaSC/SEMBPC2PGQD_index_0.html>.

Noble Wilford, John. "Jan H Oort, Dutch Astronomer In Forefront of Field , Dies at 92" The New York Times, 12 November 1992. <http://www.nytimes.com/1992/11/12/us/jan-h-oort-dutch-astronomer-in-forefront-of-field-dies-at-92.html>

APOD 4.2

Oops! Messier Moment! In this photograph taken in a field adjacent to Tänndalen, Sweden, the comet PanSTARRS soars through the northern skies, brightness rivaling that of M31, the Andromeda Galaxy. Thus the two are both seen bright in the sky, along with the double cluster h and chi Persei along the Milky Way, which can be used as a guide to the aplha star of Cygnus, Deneb.