This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the globular cluster Terzan 1. Lying around 20,000 light-years from us in the constellation of Scorpius (The Scorpion), it is one of about 150 globular clusters belonging to our galaxy, the Milky Way.
Typical globular clusters are collections of around a hundred thousand stars, held together by their mutual gravitational attraction in a spherical shape a few hundred light-years across. It is thought that every galaxy has a population of globular clusters. Some, like the Milky Way, have a few hundred, while giant elliptical galaxies can have several thousand.
They contain some of the oldest stars in a galaxy, hence the reddish colors of the stars in this image — the bright blue ones are foreground stars, not part of the cluster. The ages of the stars in the globular cluster tell us that they were formed during the early stages of galaxy formation! Studying them can also help us to understand how galaxies formed.
Terzan 1, like many globular clusters, is a source of X-rays. It is likely that these X-rays come from binary star systems that contain a dense neutron star and a normal star. The neutron star drags material from the companion star, causing a burst of X-ray emission. The system then enters a quiescent phase in which the neutron star cools, giving off X-ray emission with different characteristics, before enough material from the companion builds up to trigger another outburst.
Source: NASA press release
We now know that there is permanent liquid water on Mars, according to a paper published today in the journal Science.
Most likely, this is the best-known picture of a flag ever taken: Buzz Aldrin standing next to the first U.S. flag planted on the Moon. For those who knew their world history, it also rang some alarm bells. Only less than a century ago, back on Earth, planting a national flag in another part of the world still amounted to claiming that territory for the fatherland. Did the Stars and Stripes on the moon signify the establishment of an American colony?
Space agencies and private companies already have advanced plans to send humans to Mars in the next few years – ultimately colonizing it. And with a growing number of discoveries of Earth-like planets around nearby stars, long-distance space travel has never seemed more exciting.
The Cassini orbiter revealed many fascinating things about the Saturn system before its mission ended in September of 2017. In addition to revealing much about Saturn’s rings and the surface and atmosphere of Titan (Saturn’s largest moon), it was also responsible for the discovery of water plumes coming from Enceladus‘ southern polar region. The discovery of these plumes triggered a widespread debate about the possible existence of life in the moon’s interior.
In the last decade we have discovered thousands of planets outside our solar system and have learned that rocky, temperate worlds are numerous in our galaxy. The next step will involve asking even bigger questions. Could some of these planets host life? And if so, will we be able to recognize life elsewhere if we see it?
Billions of years ago, Earth’s atmosphere was much different than it is today. Whereas our current atmosphere is a delicate balance of nitrogen gas, oxygen and trace gases, the primordial atmosphere was the result of volcanic outgassing – composed primarily of carbon dioxide, methane, ammonia, and other harsh chemicals. In this respect, our planet’s ancient atmosphere has something in common with Mars’ current atmosphere.
It was to a great fanfare of publicity that researchers announced they had found evidence for past life on Mars in 1996. What they claimed they had discovered was a fossilized micro-organism in a Martian meteorite, which they argued was evidence that there has once been life on the Red Planet. Sadly, most scientists dismissed this claim in the decade that followed – finding other explanations for the rock’s formation.
Our solar system is a tiny but wonderfully familiar corner of the vast, dark universe – we have even been able to land spacecraft on our celestial neighbours. Yet its outer reaches are still remarkably unmapped. Now we have discovered 840 small worlds in the distant and hard-to-explore region beyond Neptune. This is the largest set of discoveries ever made, increasing the number of distant objects with well known paths around the sun by 50%.
In the search for extraterrestrial intelligence (SETI), we’ve often looked for signs of intelligence, technology and communication that are similar to our own.
The Multiverse Theory, which states that there may be multiple or even an infinite number of Universes, is a time-honored concept in cosmology and theoretical physics.