Exomoon orbiting its planet (artist’s impression): This artist’s impression depicts the exomoon candidate Kepler-1625b-i, the planet it is orbiting and the star in the centre of the star system. Kepler-1625b-i is the first exomoon candidate and, if confirmed, the first moon to be found outside the Solar System. Like many exoplanets, Kepler-1625b-i was discovered using the transit method. Exomoons are difficult to find because they are smaller than their companion planets, so their transit signal is weak, and their position in the system changes with each transit because of their orbit. This requires extensive modelling and data analysis.

Name: Kepler-1625b
Type: Milky Way : Planet : Satellite
Category: Exoplanets
Release date: 3 October 2018, 20:00
Credit: NASA, ESA, and L. Hustak (STScI)

The Ghost Nebula: IC 63 — nicknamed the Ghost Nebula — is about 550 light-years from Earth. The nebula is classified as both a reflection nebula — as it is reflecting the light of a nearby star — and as an emission nebula — as it releases hydrogen-alpha radiation. Both effects are caused by the gigantic star Gamma Cassiopeiae. The radiation of this star is also slowly causing the nebula to dissipate.

Name: IC 63
Type: Milky Way : Nebula : Appearance : EmissionMilky Way : Nebula : Appearance : Reflection
Category: Nebulae
Constellation: Cassiopeia
Distance: 600 light years
Release date: 25 October 2018, 16:00
Credit: ESA/Hubble, NASA

Ground-based view of the sky around IC 63: This image shows the sky around the nebula IC 63, nicknamed the Ghost Nebula. It was created from images forming part of the Digitized Sky Survey 2. The field of view is dominated by the bright star Gamma Cassiopeiae, which is having a profound influence on IC 63. IC 63 is only one of several nebulous structures surrounding Gamma Cassiopeiae — all of which are affected by the radiation emitted by the blue-white subgiant star.

Name: IC 63
Type: Early Universe : Nebula : Appearance : Emission : H II RegionEarly Universe : Nebula : Appearance : Reflection
Category: Nebulae
Constellation: Cassiopeia
Distance: 600 light years
Release date: 25 October 2018, 16:00
Credit: ESA/Hubble, NASA, Digitized Sky Survey 2Acknowledgement: Davide de Martin

Ground-based view of the sky around IC 63: This image shows the sky around the nebula IC 63, nicknamed the Ghost Nebula. It was created from images forming part of the Digitized Sky Survey 2. The field of view is dominated by the bright star Gamma Cassiopeiae, which is having a profound influence on IC 63. IC 63 is only one of several nebulous structures surrounding Gamma Cassiopeiae — all of which are affected by the radiation emitted by the blue-white subgiant star.

Name: IC 63
Type: Early Universe : Nebula : Appearance : Emission : H II RegionEarly Universe : Nebula : Appearance : Reflection
Category: Nebulae
Constellation: Cassiopeia
Distance: 600 light years
Release date: 25 October 2018, 16:00
Credit: ESA/Hubble, NASA, Digitized Sky Survey 2Acknowledgement: Davide de Martin

Cosmic shadow of HBC 672: This image, taken with the NASA/ESA Hubble Space Telescope shows the Serpens Nebula, a stellar nursery about 1300 light-years away. Within the nebula, in the upper right of the image, a shadow is created by the protoplanetary disc surrounding the star HBC 672. While the disc of debris is too tiny to be seen even by Hubble, its shadow is projected upon the cloud in which it was born. In this view, the feature — nicknamed the Bat Shadow — spans approximately 200 times the diameter of our own Solar System. A similar looking shadow phenomenon can be seen emanating from another young star, in the upper left of the image.

Name: HBC 672, Serpens nebula
Type: Milky Way : Star : Circumstellar Material : Disk : ProtoplanetaryMilky Way : Nebula : Appearance : Reflection
Category: Nebulae
Constellation: Serpens Cauda
Distance: 1300 light years
Release date: 31 October 2018, 18:00
Credit: NASA, ESA, and STScI