WHAT IS A NEBULA

A nebula is a giant cloud of dust and gas in space. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Other nebulae are regions where new stars are beginning to form. For this reason, some nebulae are called “star nurseries.”

An image of the Pillars of Creation in the Eagle Nebula.

These towers of cosmic dust and gas make up part of the Eagle Nebula. These so-called Pillars of Creation are part of an active star-forming region within the nebula. Credits: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

How do stars form in a nebula?

An image of the Carina Nebula, which appears as pink curtains of dust in space.

In this image of the Carina Nebula, you can spot tiny yellow and white dots inside pink dust clouds. Those tiny dots are newly-formed stars! Credit NASA/JPL-Caltech/University of Colorado

Nebulae are made of dust and gases—mostly hydrogen and helium. The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas. As these clumps get bigger and bigger, their gravity gets stronger and stronger.

Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star.

Where are nebulae?

Nebulae exist in the space between the stars—also known as interstellar space. The closest known nebula to Earth is called the Helix Nebula. It is the remnant of a dying star—possibly one like the Sun. It is approximately 700 light-years away from Earth. That means even if you could travel at the speed of light, it would still take you 700 years to get there! 

A red and blue image of the Helix Nebula.

This image might look like a creepy eyeball, but it’s actually a nebula! NASA’s Spitzer Space Telescope captured this image of the Helix Nebula, which is located in the constellation Aquarius-about 700 light-years away from Earth. Credit: NASA/JPL-Caltech/Univ. of Arizona

How do we know what nebulae look like?

Astronomers use very powerful telescopes to take pictures of faraway nebulae. Space telescopes such as NASA’s Spitzer Space Telescope and Hubble Space Telescopehave captured many images of faraway nebulae.

THE MILKY WAY

The Milky Way Galaxy is our home galaxy in the universe. It is a fairly typical barred spiral with four major arms in its disk, at least one spur, and a newly discovered outer arm. The galactic centre, which is located about 26,000 light-years from Earth, contains at least one supermassive black hole (called Sagittarius A*), and is crossed by a bar. The Milky Way began forming around 12 billion years ago and is part of a group of about 50 galaxies called the Local Group. The Andromeda Galaxy is part of this group as are numerous smaller galaxies, including the Magellanic Clouds. The Local Group itself is part of a larger gathering of galaxies called the Virgo Supercluster of galaxies.

Milky Way Galaxy Profile

Facts about the Milky Way

  • The Milky Way began as a series of dense regions in the early universe not long after the Big Bang. The first stars to form were in globular clusters that still exist. They are among the oldest stars formed in the Milky Way region.
  • The Milky Way has grown by merging with other galaxies through time. It is currently acquiring stars from a very small galaxy called the Sagittarius Dwarf Spheroidal, as well as gobbling up material from the Magellanic Clouds.
  • The Milky Way moves through space at a velocity of about 552 kilometres per second (343 miles per second) with respect to the Cosmic Microwave Background radiation.
  • The Milky Way’s central core contains a supermassive black hole. It is commonly referred to as Sagittarius A*. It contains the mass of about 4.3 million Suns.
  • The stars, gas and dust of the Milky Way all orbit the centre at a rate of about 220 kilometres per second. This constant rate for all stars at different distances from the core implies the existence of a shell of dark matter surrounding our galaxy.
  • Our galaxy will collide with Andromeda Galaxy in about 5 billion years. Some astronomers refer to our two galaxy as a binary system of giant spirals.

SPACE STATION FACTS

Space Station Facts

  • 230 individuals from 18 countries have visited the International Space Station
  • The space station has been continuously occupied since November 2000
  • An international crew of six people live and work while traveling at a speed of five miles per second, orbiting Earth about every 90 minutes.
  • In 24 hours, the space station makes 16 orbits of Earth, traveling through 16 sunrises and sunsets
  • Peggy Whitson set the record for spending the most total time living and working in space at 665 days on Sept. 2, 2017
  • The acre of solar panels that power the station means sometimes you can look up in the sky at dawn or dusk and see the spaceship flying over your home, even if you live in a big city. Find sighting opportunities at http://spotthestation.nasa.gov
  • The living and working space in the station is larger than a six-bedroom house (and has six sleeping quarters, two bathrooms, a gym, and a 360-degree view bay window).
  • To mitigate the loss of muscle and bone mass in the human body in microgravity, the astronauts work out at least two hours a day.
  • Astronauts and cosmonauts have conducted more than 205 spacewalks (and counting!) for space station construction, maintenance and repair since December 1998
  • The solar array wingspan (240 feet) is about the same length as the world’s largest passenger aircraft, the Airbus A380.
  • The large modules and other pieces of the station were delivered on 42 assembly flights, 37 on the U.S. space shuttles and five on Russian Proton/Soyuz rockets.
  • The space station is 357 feet end-to-end, one yard shy of the full length of an American football field including the end zones.
  • Eight miles of wire connects the electrical power system aboard the space station.
  • The 55-foot robotic Canadarm2 has seven different joints and two end-effectors, or hands, and is used to move entire modules, deploy science experiments and even transport spacewalking astronauts.
  • Six spaceships can be connected to the space station at once.
  • A spacecraft can arrive at the space station as soon as six hours after launching from Earth.
  • Four different cargo spacecraft deliver science, cargo and supplies: Orbital ATK’s Cygnus, SpaceX’s Dragon, JAXA’s HTV, and the Russian Progress.
  • Through Expedition 52, the microgravity laboratory has hosted more than 2,400 research investigations from researchers in more than 103 countries.
  • The station’s orbital path takes it over 90 percent of the Earth’s population, with astronauts taking millions of images of the planet below. Check them out at https://eol.jsc.nasa.gov  
  • More than 20 different research payloads can be hosted outside the station at once, including Earth sensing equipment, materials science payloads, particle physics experiments like the Alpha Magnetic Spectrometer-02 and more.
  • The space station travels an equivalent distance to the Moon and back in about a day.
  • The Water Recovery System reduces crew dependence on water delivered by a cargo spacecraft by 65 percent – from about 1 gallon a day to a third of a gallon.
  • On-orbit software monitors approximately 350,000 sensors, ensuring station and crew health and safety. 
  • The space station has an internal pressurized volume equal that of a Boeing 747.
  • More than 50 computers control the systems on the space station.
  • More than 3 million lines of software code on the ground support more than 1.5 million lines of flight software code.
  • In the International Space Station’s U.S. segment alone, more than 1.5 million lines of flight software code run on 44 computers communicating via 100 data networks transferring 400,000 signals (e.g. pressure or temperature measurements, valve positions, etc.).

International Space Station Size & Mass

  • Pressurized Module Length: 167.3 feet (73 meters)
  • Truss Length: 357.5 feet (109 meters)
  • Solar Array Length: 239.4 feet (73 meters)
  • Mass: 925,335 pounds (419,725 kilograms)
  • Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles
  • Pressurized Volume: 32,333 cubic feet (916 cubic meters)
  • With BEAM expanded: 32,898 cubic feet (932 cubic meters)
  • Power Generation: 8 solar arrays provide 75 to 90 kilowatts of power
  • Lines of Computer Code: approximately 2.3 million

GHOST HAND OF GOD

Can you see the shape of a hand in this new X-ray image? The hand might look like an X-ray from the doctor’s office, but it is actually a cloud of material ejected from a star that exploded. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has imaged the structure in high-energy X-rays for the first time, shown in blue. Lower-energy X-ray light previously detected by NASA’s Chandra X-ray Observatory is shown in green and red.

Nicknamed the “Hand of God,” this object is called a pulsar wind nebula. It’s powered by the leftover, dense core of a star that blew up in a supernova explosion. The stellar corpse, called PSR B1509-58, or B1509 for short, is a pulsar: it rapidly spins around, seven times per second, firing out a particle wind into the material around it — material that was ejected in the star’s explosion. These particles are interacting with magnetic fields around the material, causing it to glow with X-rays. The result is a cloud that, in previous images, looked like an open hand. The pulsar itself can’t be seen in this picture, but is located near the bright white spot.

One of the big mysteries of this object is whether the pulsar particles are interacting with the material in a specific way to make it look like a hand, or if the material is in fact shaped like a hand.

NuSTAR’s view is providing new clues to the puzzle. The hand actually shrinks in the NuSTAR image, looking more like a fist, as indicated by the blue color. The northern region, where the fingers are located, shrinks more than the southern part, where a jet lies, implying the two areas are physically different.

The red cloud at the end of the finger region is a different structure, called RCW 89. Astronomers think the pulsar’s wind is heating the cloud, causing it to glow with lower-energy X-ray light.

In this image, X-ray light seen by Chandra with energy ranges of 0.5 to 2 kiloelectron volts (keV) and 2 to 4 keV is shown in red and green, respectively, while X-ray light detected by NuSTAR in the higher-energy range of 7 to 25 keV is blue.