Our First Public Event This Fall Occurs Sept. 27, 7:30 - 9:00 Pm, Weather Allowing! (Check The Day Of

Interacting galaxy

Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy’s disturbing the primary galaxy’s spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.

A giant galaxy interacting with its satellites is common. A satellite’s gravity could attract one of the primary’s spiral arms, or the secondary satellite’s path could coincide with the position of the primary satellite’s and so would dive into the primary galaxy (the Sagittarius Dwarf Elliptical Galaxy into the Milky Way being an example of the latter). That can possibly trigger a small amount of star formation. Such orphaned clusters of stars were sometimes referred to as “blue blobs” before they were recognized as stars.

Colliding galaxies are common during galaxy evolution. The extremely tenuous distribution of matter in galaxies means these are not collisions in the traditional sense of the word, but rather gravitational interactions.

Colliding may lead to merging if two galaxies collide and do not have enough momentum to continue traveling after the collision. In that case, they fall back into each other and eventually merge into one galaxy after many passes through each other. If one of the colliding galaxies is much larger than the other, it will remain largely intact after the merger. The larger galaxy will look much the same, while the smaller galaxy will be stripped apart and become part of the larger galaxy. When galaxies pass through each other, unlike during mergers, they largely retain their material and shape after the pass.

Galactic collisions are now frequently simulated on computers, which use realistic physics principles, including the simulation of gravitational forces, gas dissipation phenomena, star formation, and feedback. Dynamical friction slows the relative motion galaxy pairs, which may possibly merge at some point, according to the initial relative energy of the orbits.

Astronomers have estimated the Milky Way galaxy, will collide with the Andromeda galaxy in about 4.5 billion years. It is thought that the two spiral galaxies will eventually merge to become an elliptical galaxy or perhaps a large disk galaxy.

Source

Image credit: NASA/ESA & Hubble (procesed by:  Steve Byrne & Judy Schmidt)

Animation

Comet Nishimura Credit: Peter Kennett

So gorgeous! Here's the NASA article to go with the pic.

Christmas Tree Cluster

NASA

Planet Venus as seen by the Japanese spacecraft Akatsuki built by Institute of Space & Astronautical Science/Japan Aerospace Exploration Agency

Picture of the Day!

NASA's James Webb Space Telescope has captured a stunning image of the iconic Pillars of Creation, a region where new stars are being born within thick clouds of gas and dust. The three-dimensional pillars resemble towering rock formations, yet they are much more porous. Composed of cool interstellar gas and dust, they sometimes appear semi-transparent in near-infrared light.

Dusty regions like these are often the places where stars form. In fact, there are two notable stars—V633 (top left of center) and V376 Cassiopeiae (bottom left)—in this image from the Hubble Space Telescope.

These stars have yet to start fusing hydrogen in their cores, and continue to accumulate mass. As they do this, much of the material they ingest gets shot back out as energetic jets. For these young stars, these jets can contain as much mass as Earth has.

Credit: ESA/Hubble & NASA; Gilles Chapdelaine.

ALT TEXT: A protostar in the process of forming. Above the center, at 11 o’clock, is a bright, white star. To the bottom right of this star is a large cavity, surrounded by dark brown gas and dust. This surrounding dust fills the image with the exception of another small cavity toward the bottom left. At about 4 o’clock in this cavity, there is another bright, white star. Smaller white stars are spread throughout the image.

NASA Science

How Gravity Warps Light - NASA Science

Gravity is obviously pretty important. It holds your feet down to Earth so you don’t fly away into space, and (equally important) it keeps y

Article of the Day!

"How Gravity Warps Light" from NASA Universe Web Team

The Dragon's Egg Nebula, NGC 6164 // Daniel Stern

We were extremely fortunate to have Jocelyn Bell Burnell as a virtual guest in a women in science class! She was a pleasure to listen to and continues to be an inspiration.

Navigating Deep Space by Starlight

On August 6, 1967, astrophysicist Jocelyn Bell Burnell noticed a blip in her radio telescope data. And then another. Eventually, Bell Burnell figured out that these blips, or pulses, were not from people or machines.

The blips were constant. There was something in space that was pulsing in a regular pattern, and Bell Burnell figured out that it was a pulsar: a rapidly spinning neutron star emitting beams of light. Neutron stars are superdense objects created when a massive star dies. Not only are they dense, but neutron stars can also spin really fast! Every star we observe spins, and due to a property called angular momentum, as a collapsing star gets smaller and denser, it spins faster. It’s like how ice skaters spin faster as they bring their arms closer to their bodies and make the space that they take up smaller.

The pulses of light coming from these whirling stars are like the beacons spinning at the tops of lighthouses that help sailors safely approach the shore. As the pulsar spins, beams of radio waves (and other types of light) are swept out into the universe with each turn. The light appears and disappears from our view each time the star rotates.

After decades of studying pulsars, astronomers wondered—could they serve as cosmic beacons to help future space explorers navigate the universe? To see if it could work, scientists needed to do some testing!

First, it was important to gather more data. NASA’s NICER, or Neutron star Interior Composition Explorer, is a telescope that was installed aboard the International Space Station in 2017. Its goal is to find out things about neutron stars like their sizes and densities, using an array of 56 special X-ray concentrators and sensitive detectors to capture and measure pulsars’ light.

But how can we use these X-ray pulses as navigational tools? Enter SEXTANT, or Station Explorer for X-ray Timing and Navigation Technology. If NICER was your phone, SEXTANT would be like an app on it.  

During the first few years of NICER’s observations, SEXTANT created an on-board navigation system using NICER’s pulsar data. It worked by measuring the consistent timing between each pulsar’s pulses to map a set of cosmic beacons.

When calculating position or location, extremely accurate timekeeping is essential. We usually rely on atomic clocks, which use the predictable fluctuations of atoms to tick away the seconds. These atomic clocks can be located on the ground or in space, like the ones on GPS satellites. However, our GPS system only works on or close to Earth, and onboard atomic clocks can be expensive and heavy. Using pulsar observations instead could give us free and reliable “clocks” for navigation. During its experiment, SEXTANT was able to successfully determine the space station’s orbital position!

We can calculate distances using the time taken for a signal to travel between two objects to determine a spacecraft’s approximate location relative to those objects. However, we would need to observe more pulsars to pinpoint a more exact location of a spacecraft. As SEXTANT gathered signals from multiple pulsars, it could more accurately derive its position in space.

So, imagine you are an astronaut on a lengthy journey to the outer solar system. You could use the technology developed by SEXTANT to help plot your course. Since pulsars are reliable and consistent in their spins, you wouldn’t need Wi-Fi or cell service to figure out where you were in relation to your destination. The pulsar-based navigation data could even help you figure out your ETA!

None of these missions or experiments would be possible without Jocelyn Bell Burnell’s keen eye for an odd spot in her radio data decades ago, which set the stage for the idea to use spinning neutron stars as a celestial GPS. Her contribution to the field of astrophysics laid the groundwork for research benefitting the people of the future, who yearn to sail amongst the stars.  

Keep up with the latest NICER news by following NASA Universe on X and Facebook and check out the mission’s website. For more on space navigation, follow @NASASCaN on X or visit NASA’s Space Communications and Navigation website.  

Make sure to follow us on Tumblr for your regular dose of space!