OrbitalHub

ESA dixit:

“It’s the perfect meeting of old and new. Astronomers have combined recent data from ESA’s Gaia mission with a simple analysis technique from the 18th century to discover a massive star cluster that had previously escaped detection. Subsequent investigations are helping to reveal the star-forming history of our Galaxy, the Milky Way. “

Video credit: ESA

ESA dixit:

“INTEGRAL (from INTErnational Gamma-Ray Astrophysics Laboratory) observes the ever-changing, powerful, and violent cosmos. It is the first space observatory that can simultaneously observe objects in gamma rays, X-rays, and visible light. The spacecraft travels in a geosynchronous highly eccentric orbit with high perigee in order to provide long periods of uninterrupted observation with nearly constant background and away from the radiation belts. Over time, the perigee and apogee have changed, as has the plane of the orbit.

In 2015, spacecraft operators conducted four thruster burns that were carefully designed to ensure that the satellite’s eventual entry into the atmosphere in 2029 will meet the Agency’s guidelines for minimising space debris. The orbital changes introduced during these manoeuvres are highlighted in blue. Making these disposal manoeuvres so early also minimises fuel usage, allowing ESA to exploit the satellite’s lifetime to the fullest.

By revealing both the diffuse emission from our Galaxy, the Milky Way, and the population of individual sources that shine brightly at these energies in our Galaxy and beyond, INTEGRAL has broadened our understanding of the high-energy Universe.”

Video credit: ESA/ScienceOffice.org

NASA dixit:

“Though the Webb telescope will focus on stars and galaxies approximately 13.5 billion light-years away, its sight goes through a similar process as you would if you underwent laser vision correction surgery to be able to focus on an object 10 feet across the room. In orbit at Earth’s second Lagrange point (L2), far from the help of a terrestrial doctor, Webb will use its near-infrared camera (NIRCam) instrument to help align its primary mirror segments about 40 days after launch, once they have unfolded from their unaligned stowed position and cooled to their operating temperatures.

Laser vision correction surgery reshapes the cornea of the eye to remove imperfections that cause vision problems like nearsightedness. The cornea is the surface of the eye; it helps focus rays of light on the retina at the back of the eye, and though it appears to be uniform and smooth, it can be misshapen and pockmarked with dents, dimples, and other imperfections that can affect a person’s sight. The relative positioning of Webb’s primary mirror segments after launch will be the equivalent of these corneal imperfections, and engineers on Earth will need to make corrections to the mirrors’ positions to bring them into alignment, ensuring they will produce sharp, focused images.”

Eric Villard (InuTec, LLC): Writer

Michael McClare (KBRwyle): Producer

Michael P. Menzel (AIMM): Producer

Michael P. Menzel (AIMM): Video Editor

Video credit: NASA Goddard

ESA dixit:

“As the US enjoyed a total solar eclipse on 21 August 2017, ESA’s Sun-watching Proba-2 satellite captured three partial eclipses from its viewpoint, 800 km above Earth. Proba-2 orbits Earth about 14.5 times per day, and thanks to the constant change in viewing angle, it dipped in and out of the Moon’s shadow several times during the solar eclipse. The Proba-2 images were taken by the SWAP imager, and show the solar disc in extreme-ultraviolet light to capture its turbulent surface and swirling corona corresponding to temperatures of about a million degrees.”

Video credit: ESA

NASA dixit:

“An active region on the sun — an area of intense and complex magnetic fields — has rotated into view on the sun and seems to be growing rather quickly in this video captured by NASA’s Solar Dynamics Observatory between July 5-11, 2017. Such sunspots are a common occurrence on the sun, but are less frequent as we head toward solar minimum, which is the period of low solar activity during its regular approximately 11-year cycle. This sunspot is the first to appear after the sun was spotless for two days, and it is the only sunspot group at this moment. Like freckles on the face of the sun, they appear to be small features, but size is relative: The dark core of this sunspot is actually larger than Earth.”

Video credit: NASA

Wikipedia dixit:

“Sunspots are temporary phenomena on the Sun’s photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear in pairs of opposite magnetic polarity. Their number varies according to the approximately 11-year solar cycle. Individual sunspots may last anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun, with diameters ranging from 16 km (10 mi) to 160,000 km (100,000 mi). The larger variety are visible from Earth without the aid of a telescope. They may travel at relative speeds, or proper motions, of a few hundred meters per second when they first emerge.

Indicating intense magnetic activity, sunspots accompany secondary phenomena such as coronal loops, prominences, and reconnection events. Most solar flares and coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on stars other than the Sun are commonly called starspots, and both light and dark spots have been measured.

Although they are at temperatures of roughly 3,000–4,500 K (2,700–4,200 °C), the contrast with the surrounding material at about 5,780 K (5,500 °C) leaves sunspots clearly visible as dark spots. This is because the luminance (which is essentially “brightness” in visible light) of a heated black body (closely approximated by the photosphere) at these temperatures varies extremely with temperature—considerably more so than the (temperature to the fourth power) variation in the total black-body radiation at all wavelengths (see Stefan–Boltzmann law). Isolated from the surrounding photosphere a sunspot would be brighter than the Moon.

Sunspots have two parts: the central umbra, which is the darkest part, where the magnetic field is approximately vertical (normal to the Sun’s surface) and the surrounding penumbra, which is lighter, where the magnetic field is more inclined.

Although the details of sunspot generation are still a matter of research, it appears that sunspots are the visible counterparts of magnetic flux tubes in the Sun’s convective zone that get “wound up” by differential rotation. If the stress on the tubes reaches a certain limit, they curl up and puncture the Sun’s surface. Convection is inhibited at the puncture points; the energy flux from the Sun’s interior decreases; and with it surface temperature.

The Wilson effect implies that sunspots are depressions on the Sun’s surface. Observations using the Zeeman effect show that prototypical sunspots come in pairs with opposite magnetic polarity. From cycle to cycle, the polarities of leading and trailing (with respect to the solar rotation) sunspots change from north/south to south/north and back. Sunspots usually appear in groups.

Magnetic pressure should tend to remove field concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days to weeks. In 2001, observations from the Solar and Heliospheric Observatory (SOHO) using sound waves traveling below the photosphere (local helioseismology) were used to develop a three-dimensional image of the internal structure below sunspots; these observations show that a powerful downdraft underneath each sunspot, forms a rotating vortex that sustains the concentrated magnetic field.”

Video credit: NASA Goddard