Frequently Asked Questions

With a site of this size, and the quantity of imagery available, there are always some questions that arise. This page is intended to help answer some of the more common ones.

Site Questions
  1. Why do the images redirect me to another server?
  2. Why can't I just download the larger files directly?
  3. I found a really cool image that I want to use for something, what is the policy for letting me?
BitTorrent Questions
  1. What is BitTorrent?
  2. So ... What is BitTorrent?
  3. I thought P2P and Filesharing were illegal!
  4. How do I download BitTorrent files?
  5. How does it work?
  6. Isn't that insecure?
  7. What should I be aware of with BitTorrent?

Site Questions

Why do the images redirect me to another server?
With the quantity of imagery, it was determined that having a single image server available for serving up imagery was preferable to the old practice of keeping all files on the single server. This way, both servers can be optimized for handling their tasks, providing a better end user experience.
Why can't I just download the larger files directly?
When the Visible Earth relaunched in 2005, all imagery on the site was available for immediate HTTP download. Unfortunately, this started to generate maintenance problems, as folks downloading the larger Blue Marble imagery (~400M) would be connected to the server for a very long time. Frequently they would be forcibly disconnected for maintenance, causing their downloads to abort. When Blue Marble: Next Generation launched, we had a large influx of files of equal, and LARGER, sizes. Since this would require more people to be dropped regularly, we decided to look for other ways of resolving the download options.
I found a really cool image that I want to use for something, what is the policy for letting me?
We provide the imagery for everyone to view, use, and admire. If you are planning to distribute the image with or in something, please have a look at our Terms of Use document.

Bit Torrent

What is BitTorrent?
BitTorrent is a distributed peer-to-peer filesharing protocol. It allows many people to download an object (imagery in our case), without overstraining the hosting server.
So ... What is BitTorrent?
It's a protocol, like HTTP and FTP, that allows for the distribution of large files.
I thought P2P and Filesharing were illegal!
This is a common misconception. BitTorrent, and peer-to-peer (P2P) are protocols, like HTTP and EMail. It is true that they can be used to share files illegally, but the same is true of HTTP. Our use here is legitimate, however, so you should have no need to be concerned.
How do I download BitTorrent files?
BitTorrent files (called torrents, and identifiable by the .torrent ending) are downloaded like any other file. They are then opened by the BitTorrent program (available at http://www.bittorrent.com/), which will connect to the peer network and find places that it can start fetching the file from.
How does it work?
BitTorrent connects to a central server, defined by the torrent file, which keeps track of who is working on downloading the file. The protocol then begins to request pieces of the file from all other downloaders, starting with the file parts that are least commonly available. The protocol assumes that the majority of users are not fully utilizing their bandwidth and provides the ability to download from "peers" in that extra margin. For full details, please check the Official BitTorrent site.
Isn't that insecure?
BitTorrent will only provide files to other users that you tell it to allow. Usually this will be limited to files that you are currently downloading, yourself. But after you have finished, you can allow it to continue uploading (called seeding), so that others can download easier.
What should I be aware of with BitTorrent?
You should always be careful to check that your BitTorrent client and the torrent you are downloading are both "safe". Making sure your client is safe can be mostly handled by downloading the "official" client (from http://www.bittorrent.com/, or one of the clients they link. There are many other clients available, and we have not tested them all, and we cannot speak for their validity, of course. Making sure that your torrent is safe simply means to only download torrents from "reputable sources". We like to believe that we are one. It is possible for someone to "poison" a torrent, which leads to it downloading spyware or other malicious software instead of what you thought it would download, so it is always recommended to run each file you finish downloading through an anti-virus scan before attempting to open it.